Novotel Lotus has 2 Large Suites on I believe the 25th Floor. Perhaps they don't call them "Presidential Suites". They each have an outside patio (the only rooms that have this feature). Each one has two floors, with a very large bedroom and bath with Jacuzzi Tub upstairs and large living area downstairs with access to the patio. No other rooms are two levels at this hotel. I've stayed in these rooms twice on New Years Eve and they were great for large parties.

As mentioned above, Novotel Siam Square has the CM2 Disco in the basement. It is loaded with women and would be a good stop on your bachelor party excursion.