Reporting my shopping success in case there's someone else on the forum desperately looking for the same type of bag I prefer.
For two years I've had my eyes out for a lightweight, two-wheeled bag a bit larger than carry-on size, but I've found nothing on my intermittent trips to Marshalls and TJ Maxx. A recent post reminded me this is the time of year when styles change and bags go on clearance, so I stopped at the downtown-DC locations of those chains after the RS meet-up yesterday. There were more bags than usual at both stores, so it's a good time to shop. In addition, Macy's had a lot on offer at (per signage) 50% off; I have no idea whether one could do better than the Macy's prices online.
At TJ Maxx I found an IT (itluggage.com) bag that looks like it came out of a dusty corner of a warehouse somewhere. It seems to pre-date the 4-wheeled IT bag I bought in 2015, the 4-double-wheeled IT bags I saw in 2017 and 2018, and the hard-shell IT bags now on the market.
Exterior 25" x 16.7" x 10" (incl. wheels and handle)
Interior 23.6 x 16.1" x 9.1"
Packing Capacity 3457 cu. in.
Weight 6.3 lb.
Price (TJ Maxx) $30
The bag is not expandable, and the outer pocket is very small. The bag's a bit larger (I'd guess around 1 inch longer) and definitely heavier than my super-lightweight 2015 IT bag, but the latter had single spinner wheels that turned out to be a point of failure (albeit after 90 days of heavy use). I don't need the excess packing capacity; I guess I may put a layer or two of bubble wrap in the bottom of the bag. Yes, I'd happily have paid more for a smaller, lighter bag, but this was what TJ Maxx had with two wheels in a usable size for me.
At Macy's the signage for the TravelPro Walkabout 5 indicated that line includes a 23-inch (expandable) bag, but none was on display, so I couldn't subject that one to my tape measure. If--as I suspect--the 23-inch measurement excludes wheels and handle, that would be a good size for me. But I do a lot of rolling over less-than-pristine surfaces and hate spinner wheels. The 23-incher size is on sale (if you can find it) at Macy's for $150. There's also a supposedly-22-inch expandable spinner for $140, a 23-inch "expandable rollerboard" for the same price [just reporting what I saw on the sign--I know the name and size don't make any sense], and several other sizes.