If I'm on a road trip via automobile, I pack my full D7100 DSLR outfit, which includes the 18-70mm Nikkor zoom, 50mm Nikkor Prime, Nikkor 70-300mm, and Sigma 10-20mm, along with flash and assorted bits and bobs. I then grab one of my film outfits, depending on my mood and destination. These include a Rollei 3.5f, Hasselblad 500c with 50mm, 80mm, 150mm, and 250mm lenses with both prism and waist level finders, Leica IIIC outfit with 28mm and 35mm Russian lenses and 50mm, 85mm, and 135mm Leitz lenses, Rollei SL35/Pentax Spotmatic with lenses from 28 to 200mm, or my Zeiss Super Ikonta. Each of these has its own meters (mostly Luna Pro and Sekonic ), filters, and other duplicative accessories.
When flying, I generally take the D7100 and the two zoom lenses (sometimes the 50mm prime as well) if digital seems the best for my destination and likely shooting. If I'm in a filmy kind of mood, I'll either grab the Hassy and two or three lenses, or the Leica and three lenses. If I can't make up my mind, I'll often bring the Nikon plus the Super Ikonta.
What I bring along on any trip is always a function of what I expect to shoot when I get there.
Andy