Whatever happened to action/adventure stories? Today they’re called thrillers or suspense stories.
This genre defines itself with stories that evoke an emotional thrill by placing the reader in the middle of situations such as a conspiracy or an eco-thriller.
Suspense might include an aviation story set in the past, or even a future time, and may include a familiar theme such as legal or medical thrillers. In thrillers that have espionage, exploration or treasure hunters, the protagonist’s life goes beyond the ordinary.
Thrillers are usually full of fast action and the hero always wins and leaves the reader wanting more.
Rory C. Keel
Wordsmith Six 
Rory, if you are looking for sci-fi action-packed fiction that is comfortable and safe for most ages, check out most any official Star Wars novel. Most of them I’ve read are pretty good and never trashy. I always finish wanting more!