I am using the Playtex straw sippies for Andrew because he likes drinking from them, but he isn't sophisticated enough to close the cover, so he leaves them on their sides and they drip.

Amy uses the Gerber straw sippy with handle (you press in the handle to drink) and this works great, except that some property of physics causes the milk to creep up the straw (even if it is upright) and drip out of the top if it's left standing long enough.

Are any other straw sippies drip proof? Has anyone tried the new Avent sippy?