I was chronically dehydrated for much of my life because I can't tell when I'm thirsty - my mouth doesn't send me the right signals. About 8 years years ago I bought a 48-oz Nalgene bottle which I fill up in the morning. It's big so I have a constant visual reminder right there on my desk in front of me, and I have no problems finishing it off and often refilling it in the early evening. It's absolutely improved my health.

Came here to post this. Also, vacuum insulated mugs and tumblers for hot/cold drinks as well.

Thermos sells a $30-33(?) one in two different shades of silver — the one with with green rubber(silicone?) grommets.

After performing the research, I can confirm you'll struggle to find better in any category you've been disappointed in previously.

I remember leaving mine in my car in the middle of summer. After work, I tried to pick it up, but the metal on the outside was so hot I couldn't. Inside, though, the water was cold and there was still ice sloshing around. It really impressed me.

Target sells a Zulu Ace water bottle that I really enjoy. The bottom screws off, so it's incredibly easy to clean.

Agreed entirely. Mine is a Yeti Rambler with the "chug cap". Absolutely amazing and indispensable.