For myself, there is no such thing as easy access and parking in Boston.  If you do decide on the downtown area then either the Copley area or Back Bay are best for both access and parking.  If you decide to stay out of the downtown area then I would recommend the metro west area which covers an area from Dedham to Waltham where you would have free parking, lots of hotels to chose from  and easy off the highway access.

La Quinta and Holiday Inn in Somerville are not high end hotels, but are decent and very convenient to Boston.

I pretty much agree with Elvis...  If you stay in Back Bay/Copley (where are essentially the same place), then you can take a cab and have plenty of things to do in your free time, and there is accessible parking for your visitors, but not free or inexpensive.

I'd recommend staying between Waltham and Burlington.  These will have free parking for your guests, but not a ton for you to do by foot and not really easy to get a cab.  I think you'll get more visitors west of the city, but if you stay there, you might think seriously about having a car with you.

.... park in the Pru underground garage then purchase something you had intended to buy anyway, such as a book at Barnes & Noble or a gift for the young lady.  Simply get the parking ticket validated for a reduced rate in the garage.

thriftyBob

Jezebel,

Downtown hotels always seem to offer more discreet meetings.  Sheraton, Westin in Copley are all good as are numerous others.  Nothing worse than these suburban hotels where you are he only guy walking in the lobby.

Plus, after your blissful meeting downtown, you get to hit a top restaurant or bar for relaxation.