Kevin and Diane's was perfect for my first time to Boston! It was a 20 minute walk from the convention center for the conference I attended. It's in a cute, historic area of Boston with bars, restaurants, and some shops just down the street so you feel more like a local and less like a tourist. A lot of tourist attractions are 10-20 minute car rides away. I recommend walking literally across the street to Dorchester Heights National Historic Site for the history as well as a lovely view of the city.
Kevin and Diane have a private basement with a separate entrance so it's like having you're own place. The bed was very comfortable, and even the cot I stayed on one night while friends were in town was comfortable. There was a space heater available in order to adjust the temperature, a keurig coffee machine with supplies, as well as wifi.
When I arrived it was snowing out. Kevin reached out and stayed in touch so that he could salt the entrance prior to my arrival. They were wonderful hosts that were easy to contact, communicated clearly, and made sure you had everything you needed!
I highly recommend staying with Kevin and Diane!