Aside from temples, food, night markets, Bangkok is also known for its famous floating markets. And if you haven't seen one yet, you can go to this link--->
Damnoen Saduak Floating Market. It is a nice experience to go on an actual floating market tour but if you are pressed for time or not in the mood to go to the outskirts of Bangkok, then I suggest SOOK Siam.
SOOK Siam is easily accessible via BTS Skytrain, or simply hop on to a taxi or tuktuk (depends on where you're coming from though). Or via Grab car, our preferred mode of transportation in Bangkok.