I've been in Kanchanaburi and Bangkok for Songkran (1998, 1999, 2001) and can say it was a real blast every time. Similar to the photos of Patong but Kanchanaburi did not have as many people but the scene was the same. I liked the pickup trucks with people and barrels of water driving around. I do have to admit that the water toys seem to have gotten more sophisticated as there were alot of those pvc contraptions you dipped in a barrel, filled with water, then projected the entire load on someone.
I use one of the bags for underwater photography all of the time and they work well, makes using the controls kind of awkward though, should be ok for street shooting though.
And yes, staying away from riding on a moto is very good advice.
