Okay, so I'm going back to Thailand for the 3rd time in a year - I've fell in love with the place.

So far I've seen Bangkok, Phuket and Phi Phi.

This time, I have just over 2 weeks to play with.

Not wanting to go back to Phi Phi, has anyone got any possible suggestions on where to go.
I'm more of a city person, but like a bit of beach (for a few days at most).

I was thinking of something like Bangkok (5 days), Chiang Mai (4 days), Koh Samui or similar (4 days) and then back to Bangkok for remainder.

Any ideas??