Update on the 4S: Just finished a two night stay there and as far as I am concerned this hotel is just getting better. I hadn't realized that their laundry and dry cleaning policy is that if you don't want "regular" (in by 9am, back by the afternoon), you can ask for overnight or rush (4 hours or just pressing in 1 hour) at no extra charge.
Last April I said this was my favorite Boston hotel. As of November, 2006, it still is. One additional bonus: Concierges are right on top of everything, they are very knowledgable and helpful.