Just got back from Myanmar, having spent a couple of days in Bagan.
Was lucky to find a driver with a good car (new, comfortable, efficient AC), speaks very good English, and with good knowledge of all of the temples (history, what to see inside, which temples best for sunset views, etc). Very reliable with timing too.
If anyone is looking for a driver who can also guide around Bagan temples, then I can recommend him. Fairly standard charges for the car and driver ($25 half day, $40 full day, can split the full day to morning session and afternoon/evening session with break in the middle if you wish to avoid the midday heat) - and we saved on not having to hire a separate guide.
His name is Koko, and contact details as follows: his mobile (09-3302-3175), home base mobile (09-4026-48537), primary email email@example.com, alternative email firstname.lastname@example.org.
Hope this might help out some fellow travelers.