Is the 28-inch size too big for carry-on?

Yes. At 28 inches it is a check-in bag, not a carry-on, and it exceeds carry-on limits for major US airlines. Plan to check it.

How does it compare with the softside Platinum Elite?

The hardside protects contents from crushing and moisture but has no exterior pockets and less expandability. The softside version packs more flexibly and has outside pockets.

What is the shell made of?

A polycarbonate hardside shell that flexes under impact and returns to shape, rather than a rigid ABS or aluminum shell.

Does it have spinner wheels?

Yes. It has four dual-spinner wheels so it rolls upright on all sides, which makes it easier to maneuver in airports than two-wheel cases.

Is it good for a two-week trip?

Yes. The large capacity suits a week or more of clothing, and the hard shell protects packed items. Packing cubes help keep it organized since there are no exterior pockets.