Dinner reservations can be made until 11:30 PM, at least when I was there. The club then stayed open until 2:00 AM. All of that may have changed due to Thaksin's new 'early close' rule. I would email them to check on that. The Bangkok Post or The Nation may help, too.
http://www.bangkokpost.com
http://www.nationmultimedia.com
FYI: I had the most fun when I went to Ministry of Sound on Suk Soi 12. This place is right next to Cabbages and Condoms; a restaurant that supports one of Thailand's only family planning agencies. I recommend both. Food at C&C darn good; you can sit inside in AC or out in the garden patio. It's a pretty good meal for a great cause. MOS just rocked; great music, fantastic sound system and a very smart layout with a diverse crowd. Give it a try; they are London based and can also be found on the web.