I put the Fuze in my shirt pocket. I don't have a case or skin for it. The problem with putting it in a pants pocket is that it may be subject to plenty of stress. Imo a jacket or shirt pocket would be better.
If you want more expandability, much better video, and much longer battery life than the Fuze, then buy the Cowon D2. The D2 has battery life listed as 52 hours for audio. It has a full sized SDHC card slot, a 2.5" display. It also navitagates by a choice of folders or tags. It is around the size of the Fuze in 2 dimensions, but twice as thick and 50% heavier than the Fuze. The D2 is also a favorite here. I almost bought a D2, but bought the Fuze instead. The thing that annoys me most about the Fuze and Clip is navigation by tags.