I got DD a KK, but usually we're never far away from a source of water and a place where I can ask for a real glass. For our next trip to the desert I might invest in some bota bags or something. (now my strictly vegan friends will hurl things at me)
We have KKs with the sports cap. I like the wide mouth of the KK - I can fit ice cubes in it but the sports cap chirps loudly and is too embarassing for my kids to use.
I actually much, much prefer the FunTainers or Foogo's from Thermos. They are stainless steel and have a straw. They have a wide mouth for ice cubes and they keep things icy cold without the sweating on the outside of the bottle.
Also, they are easily found at Target, ToysRUs and other stores.