It's always Chiang Mai - and get yourself down to the judges area by the Ping River.  All the floats and performers go through this area - and it's exceptional to watch. Around you/behind you you'll see thousands of lanterns flying, watch continual, amazing firework displays, and of course - the river is lined with people participating. Jump on on one of the lamp post columns - and get the best view if you have your camera with you.

How to get access to the non tourist Loy Kratong?

I heard there was 2 different events.

The one I'm interested in is the one where 1000's of monks circle that 'thing' with candles lit, and lanterns a plenty are lit dripping wax onto your head.

Think I'll try Khon Kaen for the festival. Chiang Mai looks good, but it's the opposite direction.

Here's a film clip from a band called Powderfinger. It was filmed in CM during Loy Kratong....