You may want to try Zelda's on Thames St. It has a somewhat similar vibe as Tucker's. Although nothing in Newport comes really close to the original Tucker's. Agree on Bouchard's if you want something in high end classic French. For fish you cannot beat Scales & Shells also on Thames.
It is called Malt - it's a very different vibe, but has some of the same dishes - I find it more fun to sit at the bar and I like the appetizers there. Maybe try Bouchards, it's a classic french restaurant, very good, much butter.