I use UV filters. So do most of the photographers I travel with. I'm often shooting in dusty environments where I'm moving around a lot. The filter is cheap insurance. Any nominal degradation of IQ is worth it for the protection. A circular polarizer can dramatically improve the look of outdoor shots, and should be a part of any photographer's kit. UV is more of a judgment call.
When I'm shooting on a tripod or doing indoor work or portraiture, the filter comes off because IQ becomes paramount. Of course, in those cases I'm not really using my Q anyway.