Ko Samui vs Bangkok vs Rayong vs Chiang Mai?

[Egg man]

I know that Thailand has beaches, mountains, jungles, city life, rural life etc, toursity areas, non touristy areas etc.

Anyway, I am interested in going to Thailand for a gap year. I have to stay at one fixed place so I can't travel to all the destinations. I have to choose between Ko Samui, Bangkok, Rayong and Chiang Mai
Bangkok
Rayon
Surin
Ko Samui & Surat Thani
Chiang Mai & Chiang Rai

I am not sure where to go because I like beaches, I like mountains, I like jungles, I like rural areas, but I also like busy areas - basically everywhere sounds amazing and so I can't decide!!! If you had to choose one place to go from that list, where would you choose?

If it helps, I will be teaching in a school. I will be staying with a Thai family, so preferably a more wealthy area so that I will stay in a nicer house.


Also, when would be the best time to go? I guess this will depend on where I go because the temperature changes depending on where I go and what time of the year it is. I have a choice of going in either November or late May.