Natalie, we've carried those small drawstring bags before, and those are fine. You can always stick them under your feet on the bigger rides.Also, a lot of new mobile applications have been created recently with maps of the parks, wait times, etc. beamed right to your phone! Here are a couple:
Real time line wait times: http://m.touringplans.com/
Park Maps and Times Guides: http://disneyparks.disney.go.com/blog/2009/10/mobile-magic-first-disney-parks-mobile-app-details-screen-shots-unveiled/
Woopsie, looks like I hit enter too soon on this one