Went last summer, 40 year old married man with his wife. Had a great time, stayed in the North End (hundreds of amazing italian restaurants) at the Fairmont Battery Wharf (Gold Floor) It was amazing. One thing you definitely need to do is this:
http://www.tripadvisor.ca/ShowUserRe...achusetts.html
We used it for two days, it is like your own personal taxi and it tells you all about the city. We went to a Sox game (afternoon) and used it to get to and from the stadium. One place you need to eat at is Regina Pizzeria, it is the best pizza i have ever had in my life. And i consider myself a pizza expert, hahaha. It is an amazing town. Beers at Cheers, take the tour to Harvard and Cambridge. You can't go wrong, my wife and i would go back in a second.