I know, we do Mexican a lot. Hey, I'm from Southern California. However, Bourbon Street does an AMAZING buffet. I went for the first time and fell in love. The food is great. Not too expensive 320 baht, if I remember correctly. The buffet has everything, even for the vegetarians.
Give me a call if you have any questions, or can't find the place. (Near BTS Ekami). The link to the web-site should provide you with enough info.