Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 18:40 and arrives at Koh Samui Samui International Airport at 19:50.
The flighttime is about 1h 10m. The distance travelled ("as the bird flies"): 113 Km. So the average speed is roughly 97 Km.
The best day to arrive at Bangkok is Thursday and it would be best to avoid Tuesday, as prices are on average 39.76% higher than on Thursday. (Average prices, based on 5039564 datapoints.)
We have a lot more statistics for flights PG 177 and between Bangkok and Koh Samui.