Just wandering by the water isle in the local supermarket I noticed there is a wide variety of water bottles to choose from.
I like that there is quite a few with "clip in" rings on the top. -Saves you all that time making little clip in loops yourself for each bottle.
My wife prefers the 1.5 long thin bottles because they tend to crush easier. also if any bottle breaks you don't loose so much.
If you can find bottles that have a wide mount it's nice for ease of adding sports drink.
So look for: clip in point, wide mouth, and crushability.
Happy big walling!
Hans
On the topic of drinking,
On the topic of drinking, recently I've started bringing those little tubes of powdered sports drink with me on routes, since this gives me the option of making sports drink or just having plain water. Also the little tubes fit into narrow bottle mouths really well, and they always seem to be on sale at Smiths/Krogers.