P.G.
I can't remember exactly, but I alternate travel cups and regular cups still and my son is 4.5 years old. I'd just rather he have a non-spill option if he wants to drink in the living room, but in the kitchen at mealtimes he drinks from a regular cup and has for a while. I think what you're doing is fine with having a sippy for "all day" drinking. The leak proof straw cups are good for their oral development (sucking is a good thing).