I don't know if any of your LOs have had issues with using a sippy cup, but I found one that P seems to like. It's a Munchkin Sports Bottle- I got a 2-pack at Big Lots, but I think I've also seen that brand at Target and Wal-Mart.
Hope this helps someone
Re: sippy cup recommendation!
My guy loves this one. It's his fave!
I will give the munchkin one a try as well..I think it is good to have a few on hand!