I think the best thing of traveling is trying something you've never done before! And there're many interesting activities for you to try in Bangkok like Muay thai, tasting Durian(I used to hate it but there's one place for durian smoothie that changed my mind and maybe yours too), fortune telling in temple, hapkido, parkour, and so on. You can tell me what kind of traveller you are and I'll find the best for you!