Does anyone know where to find information about peak arrival times. I'm getting so fed up with crowds that I want to try planning my trips around peak arrival and departure times.

I'm getting to the point where I want to avoid Bangkok all together.

By your own experience you know what times are bottlenecks. Book you travel to depart/arrive at times outwith the bottleneck times you have already encountered.

My experience for departures is late afternoon gridlock, say around 16:00 as well as the usual 21:00 to midnight scrum. Never had a problem with night or morning departures apart from the lengthy check-in and security that US carriers insist on. Arrivals can be a mess around lunch time and definitely any time after 23:00.

You could review the AOT website or a site like Flightstats. You'll have to factor out codeshares, and factor in aircraft size/capacity/load and charters.

http://www.suvarnabhumiairport.com/flight_schedule_passenger_arrival_en.php

http://www.flightstats.com/go/FlightStatus/flightStatusByAirport.do?airportCode=BKK&airportQueryType=1

You may do well with planning an off-peak departure from BKK, but planning the arrival is more of a crap shoot. Your flight might be delayed, or other flights might be delayed and arriving at what normally would be off-peak times.