Ok! I've done my thinking so here's my two cents!
Bella - Gryffindor. She's reckless and daring, totally brave, and I don't think any other house would be right.
Edward - *sigh* I think a part of him belongs in every house. Chivalry, check. Loyalty, check. Wise, check. Cunning, check. Too difficult for me to choose one.
Alice - Gryffindor. She shows bravery all over the place. She goes against most of the family when she accepts Edward's decision about Bella, she goes to Bella even though she shouldn't, and goes to possibly die in Italy.
Esme - Hufflepuff. I think that one is kind of a given.
Emmett - Gryffindor. He's always willing to go risk his neck and plus, he reminds me of Fred and George.
Rosalie - Slytherin. Another given.
Jasper - Ravenclaw. He is very knowledgeble and he knows what everyone is feeling. I'd say say he's pretty wise.
Carlisle - Hufflepuff. He's screaming Hufflepuff. Just, loyal, patient, hard-working, and compassionate. Geez, I love that man.