My only one suggestion is to go on a one-day river cruise up the Chao Phraya River to the historic second capital of Thailand in Ayutthaya, about 75 km north of Bangkok. The first Thai capital, Sukhothai, also worth visit, is too far to do on a one-day return trip.

You can book this tour from most hotels' tour desk. It's a full-day tour. One way by cruise on the river and the return via road in a tour bus, or vice versa depending on the number of people booked. I can't remember how much it cost. You have to go to the Oriental Hotel to board the boat on your own. They don't pick you up from wherever you're staying. Please check with the tour desk for details.

I know there's plenty of temples and palaces to visit in Bangkok. For me it was just a nice needed break from the noisy and chaotic Bangkok. You will visit a summer palace built by one of the Thai kings and still used by the royal family and also the temples and ruins in Ayutthaya. This trip is also a bit different from the other city tours in that you get to see some of Thailand's idyllic coutryside.