Take the free/paid airport shuttle or A1 bus to Mo Chit (Chatuchak) then change to the Northern/Minivan service from Mo Chit Northern Terminal to Pattaya; buses start early. Total travel ~3–3.5h depending on connection.
Leave bags at the guesthouse/hotel reception or luggage lockers so you can start exploring; most hotels allow early luggage drop though check-in may be later.
A huge wooden building carved entirely by hand — visually impressive and unique to Pattaya; visit for architecture, photography and cultural sculptures. Open 08:00–18:00.
Art in Paradise is a fun indoor 3D art museum (good if hot/cloudy) open ~09:00–21:00; Thepprasit Night Market operates weekend evenings and is worth visiting if your dates match.
Eat dinner along Walking Street or the food stalls nearby; a lively area with seafood grills and many inexpensive options (open from dusk to late night).
If you want gardens instead of island trips, visit Nong Nooch for themed gardens and cultural shows — open 08:00–18:00; arriving early avoids midday heat and lets you leave for Bangkok midday.
Catch the regular bus back to Bangkok; allow ~2–3 hours depending on traffic. Choose an earlier bus to arrive in Bangkok in time for afternoon sightseeing or markets.
If you arrive in Bangkok early enough on Saturday, visit Chatuchak for local crafts, clothes and street food; open 09:00–18:00 on weekends. (If you miss it, swap for a mall or local market visit.)
Thailand's most famous historic compound and former royal residence; arrive early to beat crowds and meet the 08:30–15:30 visiting window and strict dress code (no shorts/exposed shoulders).
Use the public river ferry instead of an expensive dinner cruise to keep costs low while enjoying the riverside atmosphere; Asiatique open 17:00–23:00.