I have done a lot of travel photography. With my partner we each carry one body and 2-3 lenses on a typical trip. I much prefer pouches or a padded insert inside a conventional bag. You get a lot of flexibility and unobtrusiveness with this setup. And the downsides of more fiddly lens changes and slightly less protection are worth it to us.
Tamrac Goblin pouches weigh almost nothing and give a bit of padding. That's what we keep our gear in, while carrying a quality backpack or shoulder bag. I also tend to travel with a small soft cooler bag. We use that for picnics and keeping food fresh between accommodations, but it also works great for extra padding for long travel legs.
Multipurpose solutions keep the weight down.