Hi Jason,

3 days is a rather short visit indeed, if you fancy excitement and city life you should of course stay in Bangkok.

However if you want to take it a bit more easy just try Chiang Mai, the second largest city located in the North. Here you will find a more laid back city life with plenty of opportunities to visit the surrounding area's for trekking, biking or hiking.

I would not recommend you to go to either Phuket, Samui or Pattaya as these are tourist centers.

Anything else you would like to know?

Cheers