If you have never been, you need to visit the temple of the emerald Buddha and in general on the territory of the royal palace and nearby look into the national museum. But personally, I prefer Wat Saket (the temple of the golden mountain) and the view itself from the mountain, I advise from the early morning

Still very cool Wat Arun, especially its amazing pagoda, is worth a visit, especially good at sunrise and sunset, but at sunset I like it better. In principle, there are still many temples, you will get to some on the way, for example, if you get to Asiatique. What I advise you to do. Firstly, in one direction from or to the BTS saphan Taksin station, you can swim both on the free river tram from Asiatique, and on a longtail or a pleasure boat, +/- at sunset on Chaop Rai there is a gorgeous view, and if you sail from Wat Arun, then you will see it and take photos of sunset on ChaopRai. Secondly, on the way, if you walk from the station to Asiatique there are several pretty temples. Finally, in Asiatique you can eat in an atmospheric seafood restaurant, buy some shoes, eat cool ice cream, take a walk along the excellent promenade, even ride on the Ferris wheel. But in the evening it is crowded, and until 3 o'clock in the afternoon half of everything is closed and hot. Of the parks, of course, I advise you Lumpini, since it is in the center, you can walk somewhere along the road. There is also an excellent Benjaminiti Park nearby. In the evening, you can visit Khao San Road, the shopping street is an eternal nightmarket, or you can go to the rooftop bar (look, there are a lot of them around the city).. lovers of purely voluntary paid relationships are waiting for the cowboy

If you want an observation deck, then firstly, you can visit Bike Sky - on the 83rd floor there is a good overview

It is better not to go very early, but in the morning, while there are no crowds. Secondly, the skywalk is a viewing room with a glass floor in King Power Mahanakhon. Of the interesting things - the house-museum of Jim Thompson, architecturally beautiful and the exposition is entertaining. The Erawan Museum is interesting - a giant three-headed elephant is still steep and the vnaturi is steep, but far from the center. You can visit Sea Life Bangkok - aquarium, I love it very much It is worth going to Chinatown, well, for understandable exoticism) If you really like parks, then you are in the park Suan Luang Rama IX - it occupies 80 hectares and there are thematic zopny in Chinese, Japanese and European style. The third favorite park is Chatuchak, it has two more small neighboring parks, you can also take a great walk. Well, Chatuchak as a market is also interesting, it seems to be the largest in Southeast Asia. If you are longer, it makes sense to roll into floating markets, the same Bang Luang.