Non-touristy Buddhist temple/monastery in Bangkok?

Edit: u/siblings-niblings has answered with more than everything I needed to know 

I have a couple of friends visiting next month. Unlike all my past guests, these 2 have Tibetan roots and somewhat religious, so I am hoping to do better than my usual run of the mill recommendations. 

I am fully aware that the forms of Buddhism practiced in Tibet and Thailand are different. If I could have it all, I’d like to recommend them a temple with:

1. A long tradition and history with a deeper focus on the actual religion 
2. Not too crowded so they can spend time soaking in the details without feeling like they’re getting in the way/ inconvencing other’s 
3. A possibility for them to talk to a monk for a bit 

Hopelessly unaware of temples, my current best guess is the temple between central world and Siam paragon. 

I would be grateful for any suggestions, within 100km of Bangkok is good enough. Thanks in advance for the help.