Travelling with carry on bags only is an ongoing process. When we first started travelling on our Y2K honeymoon to Thailand, we both had 65L packs (Arc'Teryx Bora 65's) that weighed about 14kg each. Now we are down to a 40L pack for Paul and a 38L pack for Helen (Gregory J38 and Gregory Z40 from 2016) that weigh closer to 7kg each along with a small carry on personal item of about 2kg. The carry on personal items fold down to small sizes and are stored in our main packs when not in use. 7kg is a bit of a magic number these days as lots of airlines use it as the maximum carry on weight. To help keep within the airline limits we purchased a small USB travel scale.
You can check out this website for a list of the various airline carry on weight limits. The more we travel the more we figure out what we really need and what we don't.
We also used our packs to do the Annapurna Circuit in Nepal, twice :D. We feel we made a great decision to go with backpacking centric packs vs. travel packs. The full suspension on these packs allowed us to do serious backpacking which would have sucked for the back and shoulders using some of the popular travel packs. These bags we chose can be accessed via clam shell openings as well as through the top. The only thing missing from a "travel" pack is a laptop sleeve. Since we didn't have a laptop this worked out fine. When trekking we would pare down our packs to only what we needed and added some stuff like sleeping bags, hats, gloves and trekking poles. What we don't carry we leave in a cheap bag in our hotel to be picked up on our return. Here are the contents of our packs for the Annapurna circuit: Paul's pack, Helen's pack.