After building up my first gravel bike in 2011 (a 2010 Salsa Casseroll) I got rid of my road frame and have never once missed it.

Now I ride a Soma Fog Cutter which is actually more “road” like in terms of geo numbers than a lot of gravel bikes, but takes fat tires. I run 38mm Compass tires (no second wheelset) and I am left wanting nothing on any sort pf pavement, and most gravel/dirt roads.

My sig says it all for me on this.

As far as two bikes to take on the road-trip: Gravel bike with big slicks, and a mid-travel MTB. Maybe take along a set of more knoby tires for the gravel bike?