Im thinking about going to Thailand for my first time, possibly on my own. Where to go?

I am thinking about goin to Thailand on holiday for the first time, possibly on my own, I want to have a really good time and enjoy all aspects this country has to offer. I am 23 so would enjoy both the city side and the views/countryside etc. Everything, from elephant riding, to city markets and clubs. The whole shibang. As long as its safe etc Im willing to try most things, please ANY help or advice would be great. Thanks