I love pocket watches. I haven't worn a wristwatch in over a decade, so I've had a lot of pocket watches (ask sorcererdale, he's fixed a few of them!) I've found various ways to carry them. On my Pittsburgh Kilt I had a custom watch pocket sewn to the inside apron. I'm not very fond of the pouch on the belt for myself.

As for keeping it in the sporran, there's two things. One, an old-fashioned fob to make it easier to fish out, or a chain with a clip that would normally clip to the belt, but in this case to the edge of the sporran. The only downside with keeping the watch in the sporran is I keep my car keys in there too, and they'd scratch up the case of a nice watch. If I ever get around to making myself a day sporran, I'm going to stitch a watch pocket into the top back inside.