Here is one I love, and it is hard to find. A sigg flask nested into a stainless steel cup. It is oval shaped (more flat than round) so it fits in a pocket fairly well. It is much easier to carry than the round ones if you are not carrying a backpack.

Sigg Black Oval Flask with Cup

http://www.gearforadventure.com/Sigg_Black_Oval_Flask_with_Cup_p/1557.htm

It always seems that I like the things that don't sell well and they always stop making my favorite items.