Doug Salomon
I actually don't use a water bottle per se. I use a shaker bottle. I'll have a meal replacement shake for breakfast, and then just refill the bottle with water throughout the day.
This is a pretty simple piece of equipment, but so useful. It's usefulnes goes beyond keeping you hydrated while working out.
I keep my water bottle with me throughout the day and am continually drinking from it. It helps keep my appetite under control by filling me up temporarily and also by dstracting me from wanting to eat something.