Grand Palace and Wat Phra Kaew. The one sight you should not skip. Entry is around ฿500 ($15). Go at 8:30 am when gates open — by 10 am it's hot and packed. Dress code is strict: cover shoulders and knees. One warning: if someone near the gates tells you the palace is "closed for a ceremony" and offers a tuk-tuk tour instead, walk past — it's Bangkok's oldest scam and the palace is almost certainly open.
Wat Arun and Wat Pho. Both sit by the river near the Grand Palace. Wat Pho has the 46-metre reclining Buddha (about ฿300 / $9). Cross the river by public ferry for around ฿5 ($0.15) to reach Wat Arun.
Safari World and Marine Park. A drive-through safari plus dolphin, orangutan and stunt shows. It's a full day and the best pick for families. Book the combo ticket with Marine Park — buying at the gate costs more.
Chao Phraya dinner cruise. Two hours on the river past lit-up temples, with dinner on board. Most cruises have a vegetarian buffet line — check before you book. Around ฿1,200 ($35) per person.
Chatuchak Weekend Market. 15,000 stalls, Saturday and Sunday only. Go early, carry cash, and bargain politely. Skip it if crowds tire you out — Jodd Fairs night market is a calmer version.
Mahanakhon SkyWalk. Glass floor 78 storeys up. Tickets around ฿880 ($26). Sunset slots sell out first, so book a day ahead.