I took a tuk-tuk to the airport, which was quick and painless. The Siem Reap airport is quite modern, with the new terminal having been inaugurated in 2006. Despite its small size, I admired the architecture and clear design effort that went into the construction.
A quick background on this flight: since Bangkok Airways has had a monopoly on the Siem Reap - Bangkok route for many years now, they can basically charge whatever the hell they want. This one-way flight lasting approximately one hour and ten minutes cost a whopping $276.68! Fortunately, the latest news indicates that the monopoly will finally be broken in November of this year, when Cambodia Angkor Air begins service on this route, operating 4x per week. Hopefully, they will increase the frequency as demand picks up (as I'm sure it will).