Chumphon to Bangkok

Every train back to Bangkok leaves from Chumphon station in the middle of town, so you can have dinner near the night market and walk to the platform. The question is when you want to arrive. No. 86 at 22:19 reaches Krung Thep Aphiwat at 06:10 and No. 84 at 23:18 reaches it at 07:05, which is why they're the ones I'd book. The MRT Blue Line under the station starts at about 06:00, so you can ride straight into the city.

The earlier trains are worse for it. No. 44 at 20:51 is seats only and arrives at 03:45, and No. 168 at 21:20 arrives at 05:10, both before the MRT runs. The later sleepers, from No. 172 at 23:56 to No. 170 at 02:32, arrive between 07:30 and 10:50 into the morning rush, which suits anyone who isn't in a hurry. A second-class air-conditioned berth is about ฿640–730, and Bangkok-bound berths go fast in December and January.

Suwannatee's buses leave Chumphon in the morning, between about 08:00 and 10:30 depending on where you board, and reach Bangkok's Southern Terminal (Sai Tai Mai) at about 16:20, for about ฿400–475. The main bus terminal is outside town, so board at one of the pickup points the booking sites list rather than heading out to it. A van-and-van ticket leaves at 07:10 and arrives at about 16:35 for about ฿750.

The Southern Terminal is on the Thonburi side of the river, a long way from Sukhumvit and the airports, so budget a taxi on top. The bus saves about ฿250–300 on a berth and gets you in by late afternoon, but I'd pay the difference to lie down overnight.

Thai AirAsia leaves Chumphon at 09:00 and lands at Don Mueang at 10:00, and Nok Air leaves at 19:30 and lands at 20:30, about ฿1,400–1,850 on the booking sites. From mid-December AirAsia adds a 15:40. All of them go to Don Mueang, not Suvarnabhumi.

The airport is about 35 km north of town, so leave plenty of time for the drive. For a long-haul flight out of Suvarnabhumi, the 09:00 into Don Mueang leaves the afternoon free to cross Bangkok, but the 19:30 is too late to connect safely the same night.

Krung Thep Aphiwat is Bangkok's rail hub at Bang Sue, with the MRT Blue Line underneath from about 06:00 and the Dark Red Line upstairs to Don Mueang airport from 05:00. That makes an overnight train and a midday flight from Don Mueang an easy pair. For Suvarnabhumi, give yourself the morning, because it's on the far side of the city.

If you're coming off the island, Lomprayah's 15:00 and Boonsiri's 14:45 boats reach Chumphon station at 17:30 for ฿900, a few hours before the night trains, and the 15:00 boat reaches the airport at 18:00 in time for Nok Air's 19:30. Our Koh Tao to Bangkok guide has the boats and the through tickets to Khao San and the airports.