Speaking as a former Boston native, Back Bay Hilton is at a good location, especially compared to most locations in Cambridge or other suburbs.
However, if one has a choice, I would not ever recommend one to stay at either the Hilton or Sheraton, perhaps the two worst properties in downtown Boston! Instead, I would choose the Westin/Mariott/Fairmont at Copley Place for convenience, Mariott Custom House (a time share but 5000 AA miles!), and the Four Seasons and Ritz (4 Season is better) are obviously the high end choices.
The Charles Hotel at Harvard Square, Cambridge is a small and lesser known luxury hotel that is as good as the the two previously mentioned. If you go there, try to enjoy either the award winning cooking of Joey Adams at Ambrosia or Henrietta's Table, a restaurant whose emphasis is cooking with locally grown (fresh, organic) vegetables served a la carte style. Both restaurants are inside the hotel, along with Le Pli, a spa. You will also be in walking distance to Harvard and the Red Line!
Whether or not you stay at Le Meridien, be sure to go to their Saturday afternoon chocolate buffet where the desert chef(s) flexes his(their) muscle! The name pretty much says it all. Milk is optional.