About a month ago we finally found a cup that Peyton would use, and we're still loving it! We went through just about every sippy cup known to man, but all she wanted to do was chew on them. She didn't care a thing about drinking out of one, she only wanted to drink out of "adult cups".
I noticed she was always amazed by my straws, so I started looking for a good cup with a straw. I found this Playtex Straw Trainer cup and it worked wonders! It took her a few days to really figure out how to suck the liquid up, but now she's a total pro with a straw. Peyton absolutely LOVES water (we don't give her juice) so she constantly has a full cup with her.
Now that she can handle the straw, she doesn't have issues with other sippy cups. But she still prefers her straw cups over all others!