We had the same issue back in sep. Trust me stay at the airport and AVOID the traffic to downtown Bangkok. Yes the amari is a little pricey but you walk there from the terminal. We did one night there and it was great. There is a good bar downstairs and several restaurant's. You will be fresh for the next day and dont have to "worry" about getting to the airport. Spend the extra bucks!! just my 2 cents !