Our sippy cups have come to us from gifts, hand-me-downs, and a few picked up in the store. I remember when Caleb was ready for a sippy cup, and I stood in the aisle at Wal-Mart wondering how in the world I was supposed to pick. Silicone mouthpieces that looked similar to a bottle nipple, hard plastic, soft plastic, spill-proof inserts of different kinds, handles, no handles, insulated, not insulated. Good grief!
squeak squeak, squeak squeak....
Oh, it was irritating! I quickly put that cup back in the cupboard until he got more used to the idea, and opted for a different cup with a hard spout.
And that's our sippy cup saga! It really came down to the valves for us, more than anything else. Oh, and we avoided straws because straws keep a little bit of liquid in them after every sip, and it gets flicked everywhere. I think pediatricians say straws are better, but you'll have to do your own investigation on that. I gave them up for the sake of keeping my sanity.