flpab

I am going back to two wheels after this suitcase wears out. I like the spinner but not on trains, stairs or cobblestones.
I want the Lipault 2 wheeled 19 Inch next.

thursdaysd

I traveled for a decade with a backpack and day pack. Now I travel with a two-wheeled carry-on size bag (22 inch) that I check, and a day pack. It's getting harder to find two-wheeled carry-on size bags, but I don't trust those flimsy looking four wheels in the hold.

Adelaidean

I now use a 2 wheeled carry on that converts to a backpack. Don't need to put it on my back often, but on the odd occasion, it's been helpful to have hands free or not struggling on rough surfaces.

bilboburgler

given that cars often park so their bodywork is over the curb and so narrows the pavement you need a narrow wide body. Two wheels work best, 4 are useless.

20kg is too much, you need to punch in at 12kgs tops for 2 weeks including toys.