The Cambridge Inn on Main is a gorgeous property and clearly a labor of love for its owners. It's clean, convenient, well decorated and extremely peaceful. We stayed in the Cannonball Suite, and we appreciated the high ceilings, comfortable furnishings and books about the history of Cambridge. The bed was one of the most comfortable beds I've ever slept in. We will return.
I have a couple of minor issues but they're matters of personal preference so I'll list them here but they haven't impacted my overall review score.
* Bathroom is lovely and spacious but could use more flat surfaces for toiletries, contact lens cases, etc.
* As I'm currently recovering from an injury, I would've appreciated some kind of handrail when exiting the (very nice) shower. Either that or fasten the towel rail to the wall more strongly!
* The Roku Smart TVs are a good solution but I, for one, like watching local live TV when I travel. I understand that running coax in a historic building isn't practical, but you might want to look into SiliconDust's HDHomerun boxes, which would allow you to transmit a cable or over-the-air antenna signal to a tuner app on each TV. You have great WiFi onsite and this would be an effective solution (if you consider this to be a real problem).
* Washer and dryer area on the upper level was a bit cluttered and detracted from the overall level of polish in the upstairs hallway. I don't know if fire codes would allow you to conceal that area with a curtain? Might help.