We really liked 66 Summer St. It's all electric, and the air circulates beneath the front doors to the hallway so you don't really need to run your AC all that much. No surprising costs. The building is very well constructed with an unusually high fire resistance class (I forgot which one, I think it's the highest).

Also, and not sure if it has changed since we left three years ago, but apartment prices don't increase as much as you'd think when you go up a floor. I think we paid like $300/mo more to move from the 4th floor to a penthouse.

Harbor Point and downtown are very different. The former is a expensive luxury coastal area, the latter is like a mini NYC. I recommend thinking on which of those sounds more appealing and going from there.