It's good to hear that you're interested in thinking independently and trying to develop a unique architectural sensibility which appeals to you. What you need to do is back up your preferences with supporting explanations that you can justify to your professors. Do some soul-searching (which may have to extend beyond the time frame of your studio class) and get to the root of WHY that ornamentation appeals to you, and what it actually does in the context of the overall design of the building.

Some avenues to consider.

1. Ornamentation in architecture is, in some situations, currently coming back into vogue. The new technology of digital fabrication is enabling architects (and designers in other fields) to re-introduce greater levels of variety and customization in their designs, possibly allowing us to recover some of the characteristics of pre-industrial ornamentation where ornaments were individually made by hand. I'm not the best person to ask about names of specific architects for that since I'm getting kind of sick of the trend and don't have a lot of names handy, but Herzog and de Meuron really pioneered the use of applied patterns in architecture. Maybe also elements of the work of SHoP and LTL and Foreign Office, but HDM would be a closer example. I think Enric Moralles may have also done some applied ornament. You could also look at Adolf Loos or Louis Sullivan (who were both dealing with other very different ideas and issues) as quasi-precedents from the past.

2. The debates of Modernism/Late Modernism/Postmodernism, around the 1960s-80s. Especially the late modernist period when architects were trying to incorporate elements of the essence of traditional architecture (ie how the buildings felt experientially rather than just what they looked like) within a continuing pursuit of Modernism. These should be very familiar names - Paul Rudolph, Louis Kahn, etc. - but it's worth throwing out there. While we're talking about cliche examples, there *is* a lot of ornament in Frank Lloyd Wright's work which might be inspirational if you can look at it for its ideas rather than the literal forms of the work.

Some of the Postmodern stuff could also help ... a lot of times the leaders of the movement (Venturi, Stern, Graves, etc.) were trying to apply ornament with irony, which I don't think is what you are after, but it might be worth looking at the general gist of their ideas and justifications for re-introducing ornament into architecture. Some other architects make better examples - I'm partial to Aldo Rossi, who also talked a lot about issues of urban context. You could also take a peek at the work of Minoru Yamasaki if you take what you see with a serious grain of salt and don't tell your professors about it. He tried to literally stick ornament onto international style boxes and was heavily criticized for doing just such, but some of what you were talking about sounds similar.

3. Read more about the context of the Bibliotheque's time to learn why the architects did what they did - there's a good article by Neil Levine out there (titled The book and the building: Hugo's Theory of Architecture and Labrouste's Bibliothèque Sainte-Geneviève,”) about how the library design connected with the rising mass production of the book and Victor Hugo's thesis that "the book will kill the building." You could also look at the writings of Pugin/Ruskin (Ruskin for example hated cast iron ornament), but that's a tangent.

4. Architects who approach the issue of ornament from a technical point of view. I'm thinking of Renzo Piano, who starts with the building's basic technical demands (joints, louvers, etc.) but refines them in an intentional and stylized way.

Good luck!

Nonneutral gives a good summary above... I'd only add that the book The Function of Ornament by Farshid Moussavi has a good theoretical discussion of the use of ornament, and a number of clearly organized examples, including canonical buildings like Wright's Johnson Wax, and more recent work by H and DeM, Foreign Office, etc. 

And I'd add that the effort to embellish, or on the other hand clarify and simplify a building has always had some sort of theoretical basis...though not always a fully rational one (i.e. Gothic cathedrals were meant to be evocative of the glory of God, containing moments of sublime experience, while at the same time conveying the narrative of the local town, craft tradition, etc... ).

In other words, especially in school, a building shouldn't rely simply on the tenets of a given style, but should examine how and why the elements that compose that style are used, whether they are reminiscent of 60s modernist, 1910 neo-classical, or 2000s computational-baroque. 

All that comes to mind for me is the concept of "phenomenon of place" i think by shultz is the author's name, but they talk about how differnt spaces feel and how to create that feeling with architecture, you could always argue that you want to preserve that feeling you have when you are in such spaces.  Also venturi is allwasys good for arguing for buildings that look like what they should look like.  I don't always agree with his designs, but he dose make a point that ppl feel more comfortable when they get what the expect to get

I personally love this pre-modern architecture style as well, roughly 1850-1920. I don't think there are many architects that are currently working in this style: one, because the style is not fashionable amongst architects today and two, because it would be very expensive and takes a high degree of craft that is pretty rare these days. There are however a few interior designers I can think of that do non-ironic (read: not po-mo) vaguely historicist work. Roman and Williams and (dare I say) Jacques Garcia both fall within these catagories. In terms of architects, I think you could say that some of Andrew Zago's Detroit work falls within this catagory as does some of Siza and Chipperfield's work that blends the modern and the historical. I know some may say Piano does this as well, but I don't buy it. He is a modernist through and through. Finally, I know City Center gets panned by a lot of critics because it is a big, corporate Las Vegas resort, but the mish-mash of contemporary architectural styles throughout the mega-complex is really pretty interesting, and I think has some of the richness you are looking for in the Biblioteque example.

One last point, I disagree with a number of the posts above that claim that you somehow need to rationalize using this style. Bullshit. Use it because it's cool and you can create beautiful work with it. This sort of design rationalization seems so 1990s to me.

won and done you are right about it being bullshit to have to justify your taste and what you like, unforntuantly, that is the acidemic climate.  At least that is how I felt in school, that some ppl would pin up shit and talk for an hour about theory and the jury and professors would eat it up.  Then other students would pin up really nice work, but not know how to present it and "rationalize" theire thinking, and they would be crucified for it.  So i don't think it is about making what you want to do match what ppl say you should do.  I think it is doing what you want, but have the ammo in your pocket for when someone trys to beat you over the head about it.

Hence, my point was simply that good design can occur in any style; that rationalizing the style itself is a pointless exercise; the fundamental question, no matter what the style, will always be,"Is it well designed?" That's all that really matters whether you are a first year student or have been in the profession for thirty years.

Well.... yes, but when a particular style is intrinsically linked to the measure of quality, as seems to be the case in the OP's case, isn't it worth understanding why you are using it, and therefore are able to explain it? 

I'm not making the case that all ornament should be at the service of rational, logical, or functional purposes... beauty is a perfectly reasonable explanation for something, but it's also a value that can be understood socially, culturally, and historically. And therefore is something that can be explained and discussed... 

Perhaps it's not so much a question of ornament, as it is of materiality and timelessness. Stonework is beautiful, forged metal is beautiful. It would be a worthwhile exercise to study some rich materials and really push their use with regard to proportion, composition, color, and how they affect space. Carlos Scarpa and TWBTA are good precedent to look at for this.

michael hopkins is definitely happy to work in the vein of that french metal worky age of technology.

he did a great skyscraper here in tokyo (the shin marunouchi building) that is very nice.  kinda carson pirie scott (louis sullivan) meets the 21st century.  fantastic rooftop gardens on the 8th floor or so.

the idea of style being a talking point for architecture education is incredibly boring.  i'd encourage you to challenge your teachers to offer more than that.  it isn't all on you to prove your preferences.  they have to defend theirs too.  if they only got some vague ansers about honesty of construction (which is bullshit at best) you shouldn't be asked to offer anything better.  the buildings should work in ways that go beyond style though. which is not always easy either...