Wanna use my discount restaurant card!
I'm a fan of Borgo Antico. I do casual business lunches there (i.e., lunches with people I'm trying to have a nice time with, rather than impress).
While the service can be a bit too relaxed and/or a little confused and the portions aren't huge, the pasta and seafood are always very tasty and fresh and seem authentically Italian, the atmosphere in the upstairs dining room is airy and pleasant, and the price is quite reasonable (I guess even more so with a discount card!).