Forget about PIs, they're useless in the rain. I use the Craft nemos, and they're fantastic: they're snug and really keep your feet dry in downpours. The only downside is that if you walk in them a lot, they'll get torn up pretty badly. The guy at my LBS tells me booties aren't supposed to last more than a season anyway. Not sure I agree with that (especially at $50 a pair!), but until I find something better, I'm sticking with Craft.