hedgehog05,
Not sure if the "tigershow" is worthwhile to visit....... how much? not sure as the only time I went, I got in free due to my mate's connection. Patpong has kind of mellowed down lately. Nearest skytrain station is Sala Daeng.
Sinned79,
Ayuthaya, is the old capital and also a World Heritage Site. So there are quite a number of ruins around. If you google ayuthaya you might get a better picture of what it has to offer. Might need some kind of transport there as it is kind of not within walking distance.... btw, you could also visit thai-blogs.com, they do have links to various site for you to plan your holiday in the land of smiles. The hotel lobby where you'll be staying might be another option to check on tours available.
If you plan to go by train, make sure they have started work, if I am not mistaken they are currently on strike.
Slightly off track is Bang Pa In, a "Summer Palace" (correct me) for the King of Thailand, a few buildings with different type of architecture, Chinese, Thai and Western. As it is a royal palace, dress appropriately.