I bought a tuff mug a couple months ago:
Amazon.com: Zojirushi Tuff Mug in Stainless Steel: Home & Garden
I use it for cold and hot drinks. I had some iced tea in there the other day. I put the iced tea in at noon with two ice cubes. I forgot about it in my backpack and when I opened it up at 4pm the NEXT DAY, the ice cubes were still there, rather large. I throw it in my backpack with my books/laptop, it never leaks.
I went through several bottles before finding this one. It has to be imported from Japan so it will take a few days, but it's worth it. The other bottles with those complicated sipping tops are impossible to clean. After only a few weeks of use gunk starts to build up and you can't get it out. This things has a plain, wide screw-top so you can reach your whole hand in with a sponge to clean it out, and it's lined with glass so it imparts no flavors in your drink.
Can't say enough good things about it. Couldn't find anything like it in US stores. They're all either uninsulated, or have those fancy caps that you can't clean.