I use regularly both.
The Royal Garden Resort, a real Resort right on the river, is not in walking distance of any attraction, but the free boat (running every 30 minutes) brings you in about 20 minutes to the terminal Sky train station (near the Shangri-La and the Oriental Mandarin).
The very elegant JW is in walking distance of 'everything' in the Sukhumvit area - I am not so sure that wifes will enjoy a long stay in the Sukhumvit area (Nana etc being just a block away) ... but the JW is my favorite just after arrival or before departure as with it's direct access to/from the airport motorway I can avoid any traffic hassle on arrival and (even more on) departure day.