It's a long thread, but you should check out the thread on Marriott props in Phuket. I've been to each of them over the past 2.5 years, JW 1x, Renn 2x (and JW KL 1x), my immediate response is that I prefer Renaissance over JW in Phuket and flip flop between Renaissance and JW KL. I was there at all of them with my fiancee now wife. Ren prop is a bit smaller, a bit fewer amenities/FBOs than JW, but my experience is that the staff were more hospitable. We were upgraded to a Villa last time for 3 out of 5 nights on an award stay and it seems from others experiences that they upgrade Plats there more than at the JW. You can take the shuttle between the props if you want to try the other F/BOs.
F/B is more expensive at the properties, but if you do have a car, or go offsite into Phuket town or any of the smaller communities, eating is dirt cheap in Thailand. There is a small mall close to the JW property with restaurants, but I think they were priced against the resorts in the immediate vicinity.
If you go to any of these properties, I would also recommend checking out the day tours that can be arranged through the concierge, great experiences.
We liked JW KL because the beach access was better and I think the staff were even more hospitable. The pool there is awesome too. We went to BKK over the holidays... And realize that I still need to plan another trip to to JW KL. JW KL is a bit more of a trek from HKT - need to definitely prebook transportation or get a car to get out there. It's a nice drive - but when going there the first time, I took a wrong turn and ended up close by to Krabi before turning around.
(for the other longer term posters, what the heck happened to the resident Thailand expert BKKLEE - did he get kicked off FT for good?)