Shabby chic
I stayed at the Boston Park Plaza hotel for a conference. Unfortunately, I came home sick due to the fact that the air conditioning could not be turned off in my room; it was absolutely freezing in there despite turning the a/c off completely. 
In addition, my room had not been completely renovated. The shower was best described as a shelf; it was so narrow that I could not bathe facing the shower head (let me reassure you that I am not a big person, either). 
If you end up with an interior room as I did, do not expect much of a view... unless you like staring at rows and rows of windows.
On the plus side, the hotel gym was well equipped and empty if you are an early morning exerciser as I am. Plenty of towels, water, and complimentary Gatorade gel packs (if you need one!).
And, the location was superb. I spent a few pleasant hours exploring the Public Gardens, Newberry Street, and Beacon Hill. I didn't take the T but the station was very convenient. The airport was about 20-25 minutes away by taxi.
Overall, I'm sure in its heyday the Boston Park Plaza must have been a wonderful place to stay. With some upgrading, I'm sure it will return to that status someday.