Renaissance Bangkok is preferable over JW for sky train access, non proximity to Soi Arab and Soi Nana Entertainment unless you are into cheap whores and ladyboys. I don't really like the clientele in JW Bangkok. Mostly Businessmen with cheap dates, Arabs dressed in full Ninja gear and fat, loud Americans. I find Renaissance more refined. Rooms are newer and staff more personable. I even prefer Courtyard Bangkok over JW!

I would pick renaissance Phuket over JW Phuket (and you can access pools and restaurants at both properties anyways) but really enjoy JW Kao lak.