Hi again,
We were in Hua Hin, last, just before the last ASEAN meeting there (early October 2008). At the time we didn't notice any inconvenience. Since then I think they had a lot of disruption in a meeting held in Pattaya - it is always difficult to tell in Thailand. Their approach / response is somewhat different to ours (which may, actually, be good!)
As you say, strict security can be a bonus.
I am afraid that I have no knowledge of Cha-Am (we usually stay at the Anantara in Hua Hin) and until very recently, I had an old work colleague who lived there (He's now moved to near Khon Kaen).
I hope that you enjoy this area of Thailand and that the weather is kind. You can get weather forecasts from
http://www.wunderground.com/global/stations/48475.html (Hua Hin has a small airport).
Last year it was pretty good
http://www.wunderground.com/history/airport/VTPH/2008/10/6/MonthlyHistory.html (Scroll down for a pictorial view)
Enjoy your trip
Peter