What I like about Bill's, is the mom and pop atmosphere; Bill and his wife still run the shop (since 1949!) with the help of one younger guy.
They take your measurements, pull a few suits from their shelves and have you try them on. They do the alterations for you, and when it's time to pick up your suit/tuxedo, you're confident that you'll look fabulous.
They provide rentals as well as sales. My boyfriend bought a tuxedo from Bill several years ago, while my brother in law rented one a few years later, in both instances the service was great.