Well, The Oriental and The Westin being in the same bucket: rather not
I have just been returning from a 10 day stay at the Westin BKK. In BKK, in the past three yrs I had been staying at The Oriental, The Dusit Thani, Intercontinental, The Westin Grand and few others.
I would rate these hotels in that order, with the Oriental being in a seperate league. While there are sometimes (I think ludicius) discussions about rakings, I will not go into 'size of pool' or 'size of room' discussions here: this is not what the Oriental is about - it is about levels of Service, which I found consistently superior at The Oriental.
Having said that, I do think that The Westin is a fine Hotel, courteous, professional staff, convienient Exec Lounge (nice mini crème brulées, Exec Suites are fine (again, do not start comparing them with Garden Wing duplexes) and very good location to get around with the udergroud and the skytrain.