I never used to use a boot bag. I tended to either throw the power straps over my shoulder and carry therm in, or boot up at the car and wear cat tracks on the soles to walk to the base area from the parking lot.
Then I decided to take a flight for a ski trip from Seattle to Banff on a regional jet. I needed a bag to carry them on the plane with a smaller overhead compartment.
I searched for bags that fit in overhead compartments. This is what I found, the Full Tilt Boot Pack. At $74.95 it's a bargain; this is a tough, well-built, well-designed bag.
This is a front view. It has a large compartment on the outside that expands to hold a helmet, goggles, gloves, extra gloves/mittens, and even ski pant and shell jacket, if you aren't wearing those on the drive to the slopes. So it can work well as a day pack, depending on ow much gear you like to schlep.
Side view with mesh pocket.
Side view without any gear in the outer zippered compartment, so it's perfect for sliding into overhead compartments, even on regional jets. In a larger plane you'd probably be able to keep the helmet and others things stuffed in the outer compartment. For the flight I packed my helmet, goggle and outer layers in my one checked luggage bag.
Side zippered storage. I kept an extra pair of gloves there.
Here's the main "puzzle" compartment for the boots. Because the boots nestle together the space required is very compact. The flap that zippers open is nicely padded with dense foam, so when zippered closed it's the part that rests against your back when wearing it as a back pack. It feels nice and secure and the weight is close to your body since the boots are nestled vertically, rather than extending backwards and pulling you backwards. I found it's much easier to walk without struggling with the weight of the bag, much less stress on the neck and shoulders.
There are two small eyelets at the bottom to let out moisture. Maybe better draining/venting could be improved. However I didn't have any issues with the boot compartment being wet from snow, and the compartment is easy to wipe out any dirt and grit when I got back at the end of each day.
In short, this is a well-designed and well-built boot pack, and super affordable. It'll work with any boot, not just Full Tilt.