A.G.
Eat seafood!!!! Go to the main dock on the east (ish) side...I can't remember right now the name. Anywhere you go to eat there is FANTABULOUS! If you pay a bit more for fresh lahbstah that's ok bc to me there is nothing like fresh lahbstah.
We stayed a weekend there once, in some house owned by our friends' friends, so I couldn't really recommend a place. The house was on the north side (?) where the beachside was really rocky (but beautiful). But the house was within walking distance from the Breakers, which I highly recommend you visit.
When are you going? Anytime in the summer will be extremely packed and crowded. We were there in August and while it was humid during the day it was so nice and cool at night with a great breeze. So dress in summer layers.
They have good pizza there too...and gelato (fancy yogurt style shop). Make sure to sample those.
Newport is SO romantic at night. Plan on taking a stroll on the main drag with your one and only. I hope you guys have a good time!