TLDR : Answer Summary
If you're looking for a fun day trip from Bangkok with teenagers that involves animals, consider visiting Ayutthaya. This historical site allows for bike rentals to explore gardens, temples, and statues. Other options include DreamWorld and Safari World for theme park experiences. If they love animals, animal cafes are available in Bangkok, although some have closed down, so checking current reviews is advisable. Kanchanaburi is also a great trip, with the added charm of the historical Death Railway. For a unique experience, Lopburi is known for its many monkeys, though caution is advised. For indoor options, the aquarium at Siam Paragon, known as Sea Life Ocean World, is the largest in Thailand and offers impressive sights.