Whhile I realize the specific requesst was for "higher-end" hotels, I can share about some more maderatelt priced ones. Our favorite has been the Royal River, a hotel that has no external ambiance that is up the river from the central area of Bangkok. To get to the central area, you should take a water taxi/bus. A most interesting (and cheap) ride. Near main streets is the Holiday Inn, which is a great tourist walkaround area, with easy walks to the river, and a great buffeet breakfast. Our last trip (2001), we stayed at a more local (clean but eclectic) we booked through the Best Western site. The Baiyoke Suites are in a real neighborhood, with lots of local shops (Not much tourist). On an evening walk, we even encountered an elephont walking through the street outside the hotel. A more local place.