I like Sweet Lemons in Weymouth. They have 2 locations, one on Route 53 and one on Rte 18. I have only been to the one on 53. It is in a strip mall with an ItzaParty (next to the Shaw's Plaza).
We have always enjoyed our meals there. The prices are good, service is attentive and friendly and the food is consistently good.
Here's their website: http://www.sweetlemonsthai.com/
One of our favorites is in Braintree (not very far from Weymouth): Cafe Asiana on Pearl St. It's right in South Braintree Square, across the street from McDonalds, a short distance from the T station. Very attentive, friendly service (after a few visits they greet you as a "regular") and the food is fantastic. Reasonable prices, too.