If you are looking for easy access to Harvard and MIT and don't mind staying in Cambridge, the Charles Hotel is your best choice in terms of it's location. It's right on Harvard Sq, 1 min walking to Harvard and the Red Line T station. Most of the business related events at Harvard put their keynote speakers there. It's also a pleasant 15 min walk to get to the Harvard B School. It's the only 5* in Cambridge and you can get perks from Amex FHR.