I really like the Ultra Light, Big game bags by Caribou. They might be a bit more in cost than some of the other bags out there but they are awesome. They really clean up well and are like new when you are done and ready for your next hunt.
Here is a write up also as well on bag comparison on their site as well and also the tip on citric acid and such for game care.
I've also built a little bridge across a stream before in the shade with sticks and laid the game bags a crossed that and it worked very well. But not for to long the coyotes can get to it, but if making multiple trips the same day it works great.