If you don't speak Thai, ask a Thai , your hotel or local friend to call up the Phitsanulok Bus Terminal 2, Bor Kor Sor Song, since online info is often outdate...
Don't worry. There are direct buses between the two.
I don't have the heart to fight for limited space with hard-working Bangkokians on a bus. If you find a BTS ride too expensive, then better skip Krung Thep.
Korat is more fun than KK. Nearby Phimai is also interesting.
Why not book with Nakhonchai Air direct?
A lot of rain in Dec. February and March are the best months to visit.
Thanks for the info, mate.
Will be traveling to Sangkhlaburi during my upcoming two month trip to Thailand starting from Nov 13.
BTW, can tickets be purchase...