You better know these before your trip to Bangkok! Avoid detours!
1. SIM Card
It's recommended to purchase online in advance, or you can buy one after getting off the plane, as you will see SIM card stalls right after customs. I bought mine on Ctrip for 34.9 RMB, which includes unlimited data for 7 days, 50 minutes of talk time, and a phone number to register for taxi apps. If you choose a limited data plan, it's available for just over 20 RMB.
2. Exchanging Thai Baht
Priority: Exchange at domestic banks in advance > Exchange RMB cash for Thai Baht > Withdraw Thai Baht from ATMs
It's advised to exchange Thai Baht in advance domestically, as you'll need cash as soon as you leave the airport. The exchange rate at the airport is worse than in the city. In Bangkok, exchange shops are everywhere, near BTS stations, malls, and on the streets. It's good to compare rates, so don't worry too much if you run out of the Baht you exchanged in China. If you must exchange at the airport, don't do it at the shops right after customs. The ones upstairs near the departure area (3rd or 4th floor) have better rates.
ATMs charge a 220 Baht fee, except for Bank of China machines. I used a card that waives international withdrawal fees, but after the ATM fee, the rate went from 4.8 to 4.2, which is a loss. I highly discourage it! Bank of China has only two branches in Bangkok, one in Ratchada and one in Chong Nonsi. If you're not staying nearby, don't bother coming here specifically to withdraw money.
Mobile payments are accepted at: BTS ticket machines, merchants and restaurants in big malls, stores like 7-11 and Boots
Cash only places: Various night markets, street vendors, restaurants outside malls, airport rail link, taxis, MTR subway ticket purchase, massage parlors
3. Public Transportation
Thailand's BTS and MRT run until midnight. If you're staying close to a BTS or MRT station, even if you leave the airport at 11 pm, there's public transport available. The airport subway costs 45 Baht to the city and only accepts cash. BTS ticket machines accept mobile payments, while MTR subway only accepts cash. To visit the Grand Palace and Wat Arun, just take the public boat, which costs 16 Baht per person (don't end up on a boat that charges thousands per person).
4. Taxis
Downloading just Bolt and Grab is sufficient. Compared to Grab, Bolt is much cheaper, but for the cheaper car models, there are no drivers accepting orders. Only the comfort model gets orders, but it's still a lot cheaper than Grab (160 Baht with Bolt vs. 220 Baht with Grab for the same location). I recommend directly booking Bolt's comfort model and paying in cash at the end.
5. Massage Parlors
I didn't book any fancy massage parlors in advance, just walked into a suitable one near the hotel. Here's a reference for roadside massage parlor prices: 350 Baht for one hour (full body/foot), 250 Baht for half an hour.
6. Food Courts
The food courts in Bangkok's malls are very delicious, with lots of choices. The cheapest is the food court on the top floor of Terminal 21, where a coconut is only 35 Baht (50-70 Baht at other night markets and weekend markets), a coconut ice cream is 28 Baht, and a plate of fried noodles is 40 Baht. Great value for money!
7. Wat Arun
The ticket used to be 100 Baht, but from March it's 200 Baht. Take the boat from Wat Arun Pier Station for 16 Baht per person, and you'll arrive right at the ticket office. I didn't find a place to rent clothes outside, but inside the scenic area, the reference price for renting clothes is 300 Baht, including accessories and hairstyle, no makeup or photography, with a 1000 Baht cash deposit required. Renting clothes outside the scenic area should be cheaper.
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