I have no idea what your tastes are but I found both Journey to the West and the Odyssey to be very fun and exciting, with elements of what would appeal to someone about more kid-oriented stories (adventures, fantastical creatures, fighting), but written with a more mature audience in mind. Moby Dick is another I would put in this "tale of adventure" bucket but it can be polarizing with the info-dumps about whaling.

If you want to try going in a totally different direction, I am a big fan of Abe Kobo's avant-garde work, such as The Box Man or the Ark Sakura. I guarantee it's unlike anything else you've read if you've avoided straying from the kiddie pool, playing with the whole structure of the novel itself and challenging your expectations constantly.

If you want to try some nonfiction, I have rarely read a Paul Theroux travel book I was bored by and I think Ryszard Kapuscinski is also great.