I have a camelbak style bladder that I've only used a few times, and I have a water bottle with a hand strap that makes it very easy to carry which is what I have used on my long trail runs and my ultramarathon.
If you do want to leave water behind but don't want it to be too warm, you can bury the water bottle (put it in a plastic bag first) - it will stay cool that way and probably won't be touched by other runners as they'll be less likely to notice it.
You might also want to check out my tips at:
Moderating Water Temperature in Extreme Conditions @ Run to Win