Specifically on this point, I was able to check out a few of the Sherpa bags at a local Petco, though I did end up ordering off Amazon for pricing.

My latest purchase was a Sherpa Original Deluxe Pet Carrier, Large. Trip was bringing back an 8 week lab puppy DFW-LAX on AA. While AA has a maximum in-cabin size of 19" long x 13" wide x 9" high, they state that "soft-sided pet carriers such as Sherpa bags may exceed these dimensions slightly because they are collapsible." I wanted to make sure our puppy had as much room as possible. We had no issues checking in or on the flight with the large size bag.

We had a 10+ year old Sherpa bag previously and it did great for 2 cross-country lab puppy trips and then being our cats' regular vet bag. So was inclined to stay with Sherpa vs. the others. But after regular cat use our old bag smelled too much, so wanted to check into whether the new Sherpa design was more washable than the past ones? Have only tried it once, but so far so good with the new bag.