In short
Samui has the infrastructure of a small town and the geography of an island: a ring road, private hospitals, supermarkets, and an airport that spares you the eight-hour bus from Bangkok.
Chaweng is loud, Lamai quieter, Maenam and Bophut suit a long stay better.
What it really costs
More expensive than Koh Phangan at equal comfort, but the long-term rental market is far deeper.
The private airport charges high fares: coming via the ferry from Surat Thani often cuts the cost of the journey by three.
When to go
The rainfall pattern is offset from the rest of the country. The worst month is November. The best window runs December to April.
July and August stay decent, despite being the European high season.
What nobody tells you
Tap water is not drinkable and the island's waste handling is a real problem in high season.
Power cuts are frequent in the rainy season: a UPS or a power bank changes everything when you work.