I love going to Botafumeiro when I have guests visiting from abroad. The restaurant boasts one of the freshest selections of seafood in the city. It is a great place to try paella for the first time, however it will set the bar quite high. The restaurant has a very pleasant atmosphere and the old-school style waiting means you'll have one of the 40+ waiters catering to your every need.
A suggestion: If you get an appetizer one paella serving is enough for two, two servings for three.