I did Streetcar rush last week. The box office employee was very helpful, explaining things completely. Your choice is either seats in the last 2 rows of the orchestra, which are slightly blocked by the mezzanine, or seats on the sides of the mezz (I think.) I ended up taking center back orchestra seats, and they were fine- had leg room and everything.
They're offering orchestra for it? Wonderful. I rushed Pacific Overtures and got side mid-mezzanine, which were alright. They killed the tables, though. That'll be... new.
These are modern orchestra seats, made for modern behinds. :) I was very comfortable- I could even cross my legs without touching the back of the seat in front of me.