re: Where can I get the best shrimp cocktail in B. R?

Congrats on the good news lsugal. Lost my mom to the big C almost 20 years ago. I thought you were being lazy or worse yet a Yankee.

To answer your question, yes Mansur's is good.

I always enjoy my meals there. I usually get chargrilled oysters and the visiting fish prepared in one of the several options or the redfish on cedar plank, which is very good. I love sitting in the bar. There are TVs, but the sound is muted. You can hear the piano player at night from there especially if you sit at the bar. The bar area is a nice space, comfortable with several types of table options. You can be more casual in there, though there isn't a dress code for the restaurant. I enjoy hanging out in the bar and just having drinks and lots of chargrilled oysters. I think it would fit your desires quite nicely.

ETA: And, I've seen the shrimp cocktail float by. The shrimp are nice and plump.