I find my outdoorsy bike/walk and my traveling do complement each other. I've been doing it for almost 20 years and its fairly automatic for me but when I look at other passengers and see the very large luggage they bring, about 3x-10x my size of luggage, I realize the steady accumulation of changes in my traveling kit borrowed from lightening backpacking tricks. My smaller luggage helps others get their bags on and I wish more would travel lighter.
I never need so much stuff I need to check luggage. Even for weeks away, no matter how cold the place I visit although coldest I've handled is -25F.
For places I am visiting frequently I leave a few items there (biggest is shoes) and then I can travel only with a 20L backpack and in the coldest weather strap an external 3L drybag with my down parka and that's all I need. Unfortunately most of my trips are one-off destinations so I need to carry everything and 20L isn't enough.
For most other times I need about 40L at the peak which is all my clothes and my lunch, so more of a backpack which is your simple top-loading GoLite Peak with the hipbelts removed to not catch on anything. To further survive in confined flights, I have a simple daysack inside which as I get ready so sit in my seat I remove from the backpack and that makes the backpack fit in practically anything, folding over if required or resting ontop of any bags not stuffing the overhead bins.
In the daysack I have a sitmat and my laptop and high-value stuff and any food+drink I need - most flights don't feed us inside the USA contintental flights, even 6 hour Pacific-Atlantic flights.
Weaving through airports I have one backpack no wider than my torso so I can move fast, and generally do move fast.
I carry 2 work shirts and 1 work trousers and 1 work shoes, 2 underwear, and I wash a shirt and underwear each evening, one hot soapy wash sink, and one hot clean and then drip over show overnight and the next day its air-drying in the closet which I then iron and wear the next morning. I've gone up to 3 weeks doing that. Based on the temperature, I pack fleece, down, gloves, hats, Buff. A few fave items which are better for traveling that hiking are for example Paramo Reversible shirts.
I'm usually wearing a thin wicking tshirt and shorts and Keen sandals as I'm moving so fast in any temperature everyone else finds just-right, I'm too warm. I carry a fleece and windproofs which are sufficiently water-resistent an umbrella then is enough for local hotel-office type walks in the wet.
In cool conditions I carry a medium-thickness down jacket (Patagonia Sweater jacket), in colder a thick down parka (Montbell Alpine Light Parka), to get to really cold its fleece+parka+windproof to reduce the coldspots from the stitch-through of the baffles. I am thinking I might bring both my down tops for the coldest situations.
That then gets me from 0F to 110F, between a January in Chicago to a July in Phoenix.
If I'm actually doing outdoorsy stuff at the destination, I'll bring waterproofs and switch to travelling wearing hiking boots, but I never get above the 40L of the backpack. The worst place to pack for is New York, it varies cool rain through to snow so that's synthetics+down. Places like Phoenix don't need any warm clothing and places like Chicago in winter is always cold so simple down.
A few situations the "never check" has saved me hassle, being able to walk up to the earlier flight which is running late and get home earlier is nice. Having bad weather or broken aircraft cause unexpected extra nights is not an issue as my washing methods keep rolling forward indefinitely.
So that's all the good stuff. The bad stuff is fellow passengers.