We used American Formal & Bridal for my dress and all 14 tuxes.
As far as the tuxes go, they were great. The price wasn't bad, and the incentives for renting so many were great. Any alterations that were needed for the tuxes were done right away without a terribly long wait.
The dress on the other hand was difficult. I went in knowing exactly what dress I wanted. I tried it on and that was it. It was ordered and was supposed to be in in March, so that I could come back into town to have my first fitting. I called a couple of weeks before and checked and they said that it wasn't in yet, but that it would be there so I made an appointment. I showed up the day of my appointment and told them I was there for a fitting. No one had any idea that I had an appointment and to top it all off, my dress wasn't in yet. They said it was something about the Chinese New Year and what not. Fine, I understand that, however, it would have been nice to know this before I traveled 10 hours to get there for nothing. (My wedding was in KC as opposed to where I live now) Finally, my dress came in and I came back. The woman that helped me then with my bustle was great. She knew what she was doing and made it look fantastic. When I came back for the final fitting and for my bridesmaids to learn how to bustle the dress, it was a disaster. The woman who was helping then would not listen to me or my maid of honor who was down on the floor with her trying to get the thing to work. She kept telling me that however it was pinned and showed to me the first time was not possible. She was not willing to help me at all with any cooperation. Finally (because my bridesmaids could tell I was pissed), they convinced her to just give them safety pins to take care of it the night of the wedding. To top it all off, after I got the dress off, she took it from the room and dragged it on the floor. I realize she was short, however, she could have easily put it in the plastic that the dress is stored in. Needless to say, that was more stress and drama than I needed to deal with.
The two people who I did deal with while trying on my dress that were great are Becky and the owner. Becky is especially helpful. She is extremely sweet and was very helpful even with the alterations lady wasn't.
I rented groomsman tuxedos from them when they were still in their old downtown Kansas City, MO location and known as "American Formal Wear." Now they are located in the Kansas suburbs (and known as American Bridal & Tuxedo or American Formal & Bridal). I had great service and no complaints. Alterations were done while the groomsmen waited.