"Independently wealthy" and "massive trust fund" are always favorites.

Sorry, I couldn't help myself. 

Seriously, though,  I'd worry less about specific phrases than a tone of candor and honesty in describing the applicant's strengths as well as weaknesses. 

Other helpful info is the recommender's observations of the applicant in a range of situations: in reviews; at the boards; with classmates and colleagues.  This in addition, of course, to commentary on the actual design and research work.

Good luck!

Sydknee, keep in mind that there is no "perfect" letter out there - a general guide is going to be just that.  General.  When a committee reviews all aspects of a student's application, they are trying to determine whether the candidate will be a good fit with the program.  As you note, each program is different and so the "key words" for each program will vary.

Your letter will be most successful if it accurately and specifically addresses the applicant's strengths and weaknesses.  If you want to 'give good letter' you should know the program they are applying to as well as you can, and address the ways in which the particular applicant would be a good fit for that particular program.  To avoid cliches, just seek to be rigorously specific about the applicant.

Just off the top of my head, you clearly want to avoid "Jane is a hard worker and is both curious and creative," and instead you could offer something more like "Jane works tirelessly to master a range of technical skills, whether drawing, model building or digital rendering so that she can adapt them to further her own particular design vision."  Maybe "works tirelessly" is a bit cliched, and maybe you can find a better way to put something like that, but the message is that you should focus as specifically as possible on the particular character of the applicant.  Your task is to tell a story about the applicant and the more specific the better.

Best wishes

As part of the process, plan to request and meet with your faculty from whom you are seeking a letter.  Discuss your architectural education thus far and plans for graduate studies.  Share your resume, transcript, personal statement and portfolio.  Ask them what else they might need from you to ensure the best letter possible.

Provide a full list of programs to which you are applying with full addresses, deadlines, and how their reference letter system works - hard copy, online, etc.

If you wish to best impress the school, contact them prior to inquire what they look for in letters and other application materials.

Dr. Architecture.