Concierge.com's insider take:

The Excelsior vies with the Grand Hotel, its neighbor across the square, for the title of Grande Dame of the Florentine accommodation scene. Rivalry has been reduced to a minimum now that both are Starwood properties, but there are still differences in character, and for our money the Excelsior has the edge in terms of old-world charm. Though certain features (such as Heavenly Beds and the Westin Workout gym) are common to the brand, the Excelsior asserts its own sense of style in the opulent antique decor of the public areas and the staff's impeccable green livery. Renovated in 1997, the 171 guest rooms are warmly elegant, and most are pretty spacious by Italian standards. Big spenders can splash out on the presidential suite, with its huge terrace overlooking the Arno. The hotel is a little out of the way (a couple of bridges east of the Ponte Vecchio), but there are plenty of decent places to eat in the vicinity. The hotel's restaurant Orun, with its light Tuscan cuisine, offers a good alternative when you've been tramping around museums all day. Note that breakfast is not generally included in the room rate, and can be pricey.