The Charles is among the best hotels in the Boston area, and certainly the best in Cambridge—with rates to match. Unlike a lot of high-end hotels, it’s maintained a consistent guest room style: simple yet luxurious, with custom Shaker-style furnishings and abundant amenities. Floor-to-ceiling windows make the decent-sized rooms feel bigger than they are. With Harvard Square on one side and the Charles River on the other, the nine-story brick hotel draws Harvard parents and other visitors, demanding business travelers, and vacationing families. They all get the same type of personalized service the hotel lavishes on the occasional passing celebrity.