Bangkok: 2nd class air-con buses depart roughly every 30 minutes to an hour between 07:50 and 23:00 from the main bus terminal and cost between 280 and 350 baht depending on the bus company.
Two VIP air-con buses with bathrooms depart daily at 09:35 and 20:30 and cost 416 baht. Three VIP buses with bathrooms also depart from Old Sukhothai every day at 08:20, 12:30 and 21:40, costing 390 baht.
The trip to Bangkok takes about seven hours and all Bangkok-bound buses also service Phitsanulok, Kampaeng Phet, Nakhon Sawan and Ayutthaya before reaching Bangkok's Morchit (northern) bus terminal.
Chiang Mai: 2nd class air-con buses depart roughly every hour between 05:30 and 17:30, and there's also a late night bus that departs at 02:30; all buses cost 239 baht. The trip to Chiang Mai takes around 5.5 hours and all Chiang Mai-bound buses also service Lampang and Lamphun. Buses also run to Chiang Mai from old Sukhothai, departing every hour between 07:30 and 13:40 and costing 239 baht.