Lunch by Hynes Convention Center
While I am here trying to avoid a trip to Capital Grille, I cannot deny that their lunch is excellent and a good deal. They're in the Hynes.
I would most recommend the lunch at L'Espalier -- IMHO the best lunch in Boston. They're two blocks (or so) away at the Mandarin. Lunch is also a fair deal there, much cheaper than dinner and of the same quality.
Whenever I'm at Hynes, my choices are:
1. Summer Shack. I know many people here don't like it, but coming from Vegas, to me it's great for a seafood fix. Good preps on the fish, and they also make a tasty meatloaf. Right across from the Sheraton at 50 Dalton. CORRECTION: Now closed for weekday lunch through April.
2. Brasserie Jo. Love the food. Inconsistent service, though. Go left out the door of the Sheraton, and it's 2 short blocks away at 120 Huntington.
3. Chilli Duck. Not fancy, but reliably good Thai, 829 Boylston.
I worked across the street for a long time. Cafe Jaffa was (and is still) my favorite lunch in the area. It's casual, but good food.
If going for a steakhouse option, I much prefer Abe & Louie's lunch over Cap Grille.
Most options in the immediate area are pretty mediocre and overpriced.