When we moved into an old industrial space, we just got a grinder and smoothed out the concrete, then polished it. Kept it that way for 12 years. It was easy to clean, and we didn't worry about damaging it. We'd hang seamless when we needed a cove look, and built sets on it when we need them. It even photographed nicely for some fashion portraits or motorcycle shoots. Here it is with Jaime Bergman, shot with ringlight, against a textured stucco wall we had done early on.
The thing is, if you paint a concrete floor, especially a former garage, you have to prep it with muriatic acid to get all oil residue out of the concrete. Then you prep it with some kind of solvent (I forget which) and paint it with special concrete paint. It will look great for about a month, then you'll think about painting it again. After doing this at my first two studios, I said no way for the next one. I do know some guys with white built-in coves (make a frame and use drywall and stucco to make the curve) but there is an art to it, and its also a pain to keep clean. And if you want another color, you either end up using seamless paper anyway, or you acknowledge that it will take several coats of paint to get back to white. Unless you do a lot of white cove work, its not worth it.
One funny thing I used to do sometimes. One of my dogs, Puliki, used to chase tennis balls, and when she was ready for a bath, I'd take her into the studio (I took her to work everyday) and and throw the ball at the back wall like playing handball. She'd run after it and slip on the polished floor, and slide into the wall. It was fun to watch for a while, and helped keep the floor clean. Then she was really ready for a bath. Here she is on that floor a little more relaxed.
Andy Pearlman Studio