Dont worry about the scratches. If you get GOOD hardwood and proper finish you have nothing to worry about. The house I grew up in has hardwood floors. My sister and I use to roller skate in the hallway. It has not been re finished for 40 years and still looks great. No scratches you can see unless you get down on your hands and knees (yes we know that's your favorite position ) and look close.

Agree with the 100% hardwood finish. I like the on wheels idea unless you are having electrical connection but you can easily put in-floor plug. Think ahead.

PS I LOL at the comment on expansion/contraction. My moms is 50+ years old and not one gap or crack.