I went to see Les Misérables, and it was great. The Rep has a very nice, small theater. There probably isn't a bad seat in the house. I sat on the first row of the orchestra level, and sitting right there up front is a really cool experience. There's no orchestra pit and nothing separating you from the front of the stage. If the action is taking place up stage, though, you have to look up at an odd angle, so if that would bother you, choose some seats a little further back.
There's a fairly large lobby with lots of space to mill around. The stage door is inside opposite the bathrooms.