I am sorry that I did not see this post earlier. In the event that you are still checking, I live in Lafayette and have a few suggestions.
While in the opposite direction of Breaux Bridge (about 25 minutes from Laf.), our favorite place for oysters in the area is Black's Oyster Bar in Abbeville. Their raw oysters (always cold), fried oysters, and chargrilled oysters are great. Shucks in Abbeville has tasty oysters too, but in my opinion, lacks the atmosphere of Blacks. Both places have tasty salads with broiled oysters.
In Lafayette, we have enjoyed Don's on Johnston Street. As stated in an earlier post, we are getting late in the year for raw oysters, so use your best judgment.
However, we usually eat fried oysters year round if we can find them. Our favorite Fried Oyster Po-Boy (as well as shrimp)is at Olde Tyme Grocery on St. Mary. It is near the university and has a bit of low-brow authenticity. They have their own website of the same name.
Your hotel should be able to direct you to any of these. I hope you enjoy your time in Lafayette. Ask some locals for their favorites after you get here as well.
i cant say about laf. but the best oysters in baton rouge are probably at Phils Oyster Bar on College Drive. The new location lacks some of the charm of their old place on Governemt but they do have really great oysters. That said, it is starting to get to be a bit warm for raw oysters.