For most DIY floor refinishing, a directional drum sander is a bad idea. It removes a lot of material quickly and in the wrong hands can do substantial damage. You can rent a non directional floor sander that uses an 18 x 18 inch sanding pad. This is an easily controlled efficient sander. It operates a lot like a hand sander, but is much larger, heavier and has a vacuum to control dust. This would be the right machine to use, and would minimize any hand sanding needed along edges or corners. Start with medium grits and progress to finish with 180 or finer paper, and the finish will not show cross-grain scratches.