Thailand’s two headline beach bases sell different holidays hiding behind the same postcard sunsets. Phuket and Krabi (the Ao Nang and Railay coast) are ninety minutes apart by ferry and priced a world away in structure: one is a full-service island with an airport, marinas, and every amenity chain; the other is a provincial cliff-coast where long-tail boats replace taxi stands. Neither is better — but one of them is wrong for any specific trip. Here is the comparison that actually matters, with Koh Samui as the third option for calendar reasons most guides skip.
Phuket: the complete-service island
Phuket has an international airport, golf course, hospitals of standards, and the widest hotel spectrum in Thailand — from 25-euro guesthouses in Old Town to 400-euro villas at Kamala. Its strengths: direct flights from most Asian capitals (and many European hubs in winter), 15+ beaches each with its own character (Kata for families, Nai Harn for calm, Bang Tao for long sand), and an infrastructure that absorbs children, teenagers, and grandparents simultaneously. Its costs: night-life districts that occupy whole beaches (Patong), traffic between beaches that adds 300–500 Bhat per day to any stay that moves around, and a tourist-premium on food that tracks 20–40% above mainland prices. A week for two in a decent Kata guesthouse or three-star runs 350–500 euro lodging plus transport costs for the rest.
Krabi/Ao Nang: the landscape-value base
The Krabi coast’s selling point is out the window: limestone karst shelves rising from turquoise water, of which Railay Beach — reachable only by 4-euro long-tail boats — is the postcard and Tonsai and Phra Nang the quieter sequels. Costs structure cheaper: Ao Nang guesthouses at 20–35 euro, food within mainland pricing (4–6 euro platters), and the “island-hopping day” product where a private long-tail for four costs 60–90 euro split. Four-island, Hong Islands, and Phi Phi day trips depart directly from Ao Nang’s beachfront. Its costs: fewer direct flights (via Bangkok or Singapore connections mostly), narrower high-end hotel stock, and a town that empties its beachside bars by 23:00 — a feature or a limit depending on the trip.
Koh Samui: the calendar island
The Gulf-side island runs an inverted weather window: its driest, calmest months fall where the Andaman coast (Phuket, Krabi) is in monsoon — roughly July to October. This matters more than anywhere else in Thai beach planning: the region’s rainy season is not a drizzle but a week-scale power-wash. Samui’s airport makes access gentler (difficult in other ways: fewer budget carriers, higher fares), its beaches (Chaweng’s 7 km, Lipa Noi’s calm), and its resort-leaning stock price 15–25% above the Andaman coast — a premium you pay for the right calendar. A family that must travel August makes Samui the right answer by weather alone.
The costs, side by side (two people, one week, lodging + eating + local transport)
- Phuket (Kata base): 550–750 euro
- Krabi (Ao Nang base): 400–600 euro
- Samui (Chaweng base, in-season window): 650–850 euro
All three include roughly 6 nights’ lodging, honest local eating, and day-to-day boats. The flight line to Phuket is usually the cheapest of the three; the boat-and-pier logistics to Samui may consume the island’s cost edge. Anyone juggling the longer itinerary frame — this comparison slots directly into the month structure of our Thailand month — can interpolate.
Deciding by trip shape
- Direct flights matter (short leave, young family): Phuket. Its airport product decides the trip before the beach does.
- Landscape, boat days, climbing, quiet-ish evenings: Krabi. Also the cheaper long-stay base: a month here tracks the patterns explained in our guesthouse-island economics at Thai prices.
- August or September beach quality: Samui, without hesitation — the calendar argument outranks all others.
- Night-life as a headline: Phuket (Patong earns its reputation), else Krabi’s quiet is a feature.
- The hybrid: fly into Krabi, 4 nights at Railay-side, ferry to Phuket, 3 nights at Kata — the two-island week covers both coasts’ strengths for the cost of one plus a ferry ticket.
Two honest warnings
First, “monsoon” on the Andaman coast does not mean afternoon showers: June to October sees whole days of it and boat trips cancelled — book Andaman-side weeks November to April and reserve Gulf-side exceptions for Samui. Second, beach quality varies street by street: Phuket’s Patong and Ao Nang’s town beach are service fronts, not swimming beaches — the swims are at Kata Noi, Nai Harn, and Phra Nang respectively, forty minutes or one boat ride from where the rooms actually sit. Book accommodation by walking distance to the specific beach you intend to swim at, not by the island’s name on the booking site. Both warnings are the same lesson: Thailand’s beach map rewards specificity — and penalties for vagueness appear in the weather line and the taxi receipts alike, the pattern our winter-sun guide generalises across islands everywhere.