Oh boy is your wife lucky! Have a great time in beantown! Just off the top of my head my #1 pick would be Rialto in Cambridge, it is known as one of the more "romantic" places, though $$$. Another is Biba. If you go to boston.com I believe you can get menus, directions, ratings etc. The Boston Globe reviews restaurants weekly, I think you can look up the rating at the same web site. If any others come to mind after I think more about it, I'll let you know right away. I would choose to have Sunday brunch at the Harvest, also in Harvard Square Cambridge. just a very short subway ride from Boston so don't let hat turn you off! The square is also a great place to walk around, go down to the river, walk along and hold hands. Ok, I'm getting carried away. You might want to take in a show - also check boston.com. What is her taste?
I went to that show last year - quite a spectacle! She will like it!