i've recommended the rui jin in the past (earlier in this thread, i think) and stand by my sentiments. the location is great, the gardens' serene, and the mystique "old shanghai". that having been said, getting one of the big rooms is an imperative (they cost more).

be advised that if money is no object up to your threshold, you can stay almost anywhere in the city, provided you are a decent negotiator and/or can reference any corporate agreements. if i were in that boat, i'd probably go for the portman because i like the gym or the jw marriott because it is new. i would pass on other places within striking distance (shangri-la, hyatt, westin, st. regis) because i think they're overrated. the 4 seasons would be a decent pick as well, though not necessarily better than the portman (except for the rooms) and probably not less than 150.