Unless needing to be at Copley Place, I would recommend the Sheraton Boston or W Boston. Both properties offer 4pm check-out as well as much better Platinum breakfast options.

Sheraton Boston has given me both suite and junior suite upgrades on multi-night stays. I found the Club Lounge breakfast offerings adequate with ample fresh cut fruits that included berries which I enjoy adding into yogurt.

W Boston offers $20 credit for breakfast menu options with the Market Breakfast being the best value (2 eggs, choice of bacon/sausage/ham, breakfast potatoes, tomato salad and choice of coffee/tea).

Westin Copley Place offers skimpy Platinum breakfast benefits and does not guarantee 4pm check-out. I would book accordingly.