The nearest operating airport to Prachuap Kiri Khan is Chumphon, with Nok Air and Solar Air operating the 70-minute flight to and from Bangkok's Don Muang. Fares hover somewhere between 2,000 and 3,000 baht. Once you have factored in check-in and arrival time, plus the onward transfer from Chumphon to Prachuap Kiri Khan, there really is no point in flying to Prachuap Khiri Khan.
Prachuap Kiri Khan is on the main southern railway line from Bangkok, and train makes for by far the best way to arrive -- the four-and-a-half- to six-hour journey is a pleasant one, and Prachuap's train station is centrally located, making for an easy transfer to your accommodation.
Nine trains arrive daily from Bangkok, leaving the capital throughout the day and arriving in Prachuap from midday until the early morning. On the return leg, trains to Bangkok leave Prachuap Kiri Khan mostly in the late evening and early morning, though there is one mid-afternoon departure that arrives in Bangkok in the evening. Trains cost from 168 baht all the way up to 1,612 baht for a private air-con sleeper compartment for sole occupancy -- a typical and more than sufficient second-class fan-cooled seat costs 245 baht.
Hua Hin is around an hour's ride away, with a third class seat costing as little as 49 baht, while Chumphon, the jumping off point for the islands of Ko Tao, Ko Pha Ngan and Ko Samui, is two to three hours and a 78 baht second-class seat away.
Minivans leave from several spots around Prachuap Kiri Khan, including outside the Intila Hotel opposite the night market, and just around the corner from the City Shrine. They run every half an hour to Bangkok's Sai Tai Mai (Southern) terminal for 240 baht, via Hua Hin (80 baht), Cha Am (120 baht) and Mae Khlong, in Samut Songkhram province (200 baht). Minivans also serve Chumphon for around 150 baht.
Bigger buses for Bangkok depart from opposite the 7-eleven on Phitak Chat, around the corner from the Yuttichai Hotel, take four to five hours and run between 06:00 and 01:30 at a cost of 200 baht -- buy your ticket on the bus.
From the same spot, Chumphon is served by buses from Bangkok departing Prachuap Kiri Khan throughout the day and taking around three and a half hours for 160 baht. Many of the same buses then continue to Surat Thani, taking seven hours from Prachuap and costing 210 baht. Krabi is nine hours away at 280 baht, while the 10-hour journey to Phuket costs 305 baht.
A small but sufficient number of tuk tuks ply the streets of Prachuap, and a few can usually be found hanging around by the train station. They will take you anywhere in town for around 30 baht, and further out spots like Wat Ao Noi shouldn't cost more than 100 baht or so.
There are fewer motorbike taxis but they can be flagged down in the street -- prices, which tend to be similar to those for a tuk tuk ride, should be agreed in advance. Make sure you wear a helmet.