I use Cheers, but I think that's an Aussie thing as we always say that to each other when leaving. I know a lot of N.Americans tend to say Thank You, which is nice as it works well in pretty much every situation, formal or casual.

Instead of copying the originating greeting, I would just chose one that suits your personality and stick with it, even if it is in a different language. I know Hawaiians that use Ma-halo, and Spaniards that use Hasta Luego. So why not use Wai if you are Thai? It personalises your greeting nicely!