Three hours maybe a lot, but to go anywhere but the airport maybe your only solution.
This may help:
Boston Logan help when Waiting
In BOS there's a row of rocking chairs in the AA terminal B "hallway" between the Eagle and main gates. Also there's Chinese Artwork gallery and more rocking chairs in a connection between terminal B and C , not to mention that those rocking chairs in between B & C have an excellent view of the tarmac.