Xiled1 wrote: For now I am going with the trash compactor bags (several smaller ones) and ziplocs. We'll see how that holds up.
I wouldn't trust ziplocs for anything more than backup inside of the compactor bags. Anything you keep in just a ziploc bag will get wet. Even a ziploc inside of another ziploc will not hold up well and your stuff will get wet.
I use light drybags, compactor bags, or trash bags inside of a pack with grommets.
With the compactor/trash bags, I squeeze as much air out as possible and then twist the ends instead of tying them. It makes it easier to get into them and I've never had a problem with them leaking. They are also small, light, and cheap enough to pack a spare or two.
I keep smaller items that I might want to get to without much trouble inside of wide-mouthed nalgene water bottles. These also trap enough air to add some buoyancy to the pack.
I've used the kids boogie board method before, with one strapped to the pack, and it worked great. They are cheap, light, and durable and they do have the added benefit of providing a camp chair/table/float toy. Now, I usually just fill empty spaces in my pack with pieces of those fun-noodle type pool toys. If they are positioned right, there isn't even much submersion. They aren't very useful in camp though.