Rambler Routes are established gravel routes that most likely contain chipseal surfaces and some unpaved sections. You'll find lots of flat sections as well as consistent climbing, with 1-2 challenging climbs on the routes. Expect less than half as much climbing as compared to total distance traveled.
There's a time and place for touring, but sub-24h-overnights can be some of the simplest bikepacking trips to prep for once you have a starter kit to work with.
Flyboy's Day Off is a great example of a route that suits a variety of bikes, with options to make things spicy or laid-back, and easy access to amenities along the way.