If you have more time and you want to nature tourism near Bangkok. I suggest Bang Krachao.
This place is like lung of Bangkok because It's filled with natue. The government has a law does not give this place high-rise buildings and to preserve the natural environment.
As above picture is map of Bang Krachao, It has many way go to it but one way easy to go is BTS (Bang Na station) and take a taxi or motocycle or walk to sanpawut rd and take red bus to Bang Na noak temple (วัดบางนานอก) and take a boat to Bang Krachao when you're arrive. You can rent a bicycle and ride around.
At Bang Krachao, It have many place is popular Thai people like travel, So Bang Nam phueng Foalting, Fighting fish museum, Sri Nakorn Khuen Khan park,
Bang Nam phueng Foalting Market
If you love and enjoin eat thaifood, you should travel this place because it has many restaurant noodle, rice, Pad thai, etc.
Sri Nakorn Khuen Khan park
It's a big park some people go to study nature, some people go to relax and exercise. In this park has one highlight is view of the tower
Fighting fish museum
This museum has many fighting fish species. And teach a tips how to care each fish species as well.
Aromatic Joss stick house
Here are taught how to make herbal incense. Citronella mosquito repellent or to teach a painting
Thanks picture from neju11 pantip
http://pantip.com/topic/32494078