When you are selling something, you just want to have what all the buyers are looking for, and that is granite slab.Regarding Corian, not only does it get scratched, but it is expensive to get someone to come and refinish it so the theory that the scratches can be removed is not a practical one unless you know how to do it yourself.

I've read about using ceramic tile, refinished wood floors, same colors of paint on ALL rentals to provide consistency. 

So fixing a scratch on the floor wouldn't add, but completely sanding down and refinishing them would?

This would be a potential rental once it's fixed up a bit (it also needs work, but mostly cosmetic like refinishing the hardwood floors).

I currently ran into some heating issues and have had to refinish some of it as it seems they didn't insulate the apartment properly.

spray-net kitchen refinishing.

I got a couple quotes from two different hardwood refinishers for my primary residence.

Refinish what you have - flipping this property, you are going to be looking for a specific type of buyer and you will not recover the cost of residing it in a way that preserves the architectural interest of the property.

The basement had some un-finished spaces, but most of the basement had just been beautifully re-finished with a mother in law apartment (which I was going to rent out).

Sometimes we have to paint, replace a vanity, refinish floors, remove an old tree,... you never know.