It doesn't seem necessary to hide it to me. All the bigger deployments I've seen just put APs on the ceiling. There are enough things on there (smoke detectors, lights, sprinklers) that adding another box probably wouldn't make much aesthetic difference unless you went out of your way to hide all the other things.

Aruba Networks used to make a model called the AP-65WB. The WB means "wall box" -- it basically fits in a standard wall-box, the same kind of fixture that could also hold a couple of outlets or light switches (or a combination thereof). Not sure if that unit's been replaced or retired, though. Also, it's not exactly targeted at home users.

Many of the enterprise APs with integrated antennas are designed for ceiling installation. They often have an antenna that's intended to radiate its best coverage down from the ceiling in a cone.