Phi Phi Islands day trip. The number one thing to do from Phuket. Speedboat tours hit Maya Bay, Pileh Lagoon and a snorkel stop, from around ฿1,400 ($40) with lunch. Seas are roughest June-October; take a morning tour for calmer water and fewer boats at Maya Bay.
Big Buddha. The 45-metre white statue on Nakkerd Hill. Entry is free, views cover half the island, and sunset is the best hour. Shoulders and knees covered — sarongs are lent at the gate.
Wat Chalong. Phuket's most important Buddhist temple, with tiered stupas holding relics and near-constant incense smoke. Free to enter, and a natural stop between Karon and Phuket Town — a good half-day break from the beach if you want something that isn't sand and boats.
Old Phuket Town. Painted shophouses, a weekend walking street, and the island's best cheap food. Give it half a day. It's the answer when someone asks what "things to do in Phuket city" actually means.
James Bond Island (Phang Nga Bay). Longtail or speedboat tour past the famous limestone pin, usually with sea-canoeing through caves. Calmer water than Phi Phi, so a good monsoon-season pick.
Karon Viewpoint and the beaches. Kata Noi, Karon and Freedom Beach are cleaner and calmer than Patong. Swim between the red flags only — currents are serious in monsoon.
Phuket FantaSea or Siam Niramit show. Big stage shows with dinner. Touristy but fun with kids. Around ฿1,900 ($54) with dinner; book a hotel pickup slot.
Ethical elephant sanctuary visit. No-riding sanctuaries in Phuket's interior run half-day visits — feeding and watching rescued elephants — from around ฿2,500 ($70) with hotel pickup. Anywhere offering rides or shows is one to skip.