Go to Home Depot, rent their sander, buy some sandpaper, and stain the floor yourself.

I don't know about "cool"  :)  but I think your best options are: 1, Re-carpet the existing stair treads.2, Stain or paint the existing stair treads.3, Replace the existing treads with another solid wood (to be stained or painted).If you opt for #3, you might consider hiring it out.  

Tenants love it and I use extra thick coats of dark stain if there is a lot of discoloration and damage and always double or triple up on the coats of varnish so that it can withstand a beating.

Brown stains on the walls, a little ways down from the ceiling are a sign they were cooking.

@Jon Gorham Student housing can be a great investment just make sure that you use really durable materials (high traffic carpets, stain resistant paint etc) to help the house stand up to the potential beating it will take from the tenants and remove things that break easily or increase your liability (IE ceiling fans).

The old tenants used used hair dye that stained the tub, when they left they were able to scrub off the dye but now there is a section of the tub- where about 18" x 8" of the tub enamel has been scrubbed off and is discolored and rough.

I went to some of the local places that rehabbers use, but really didn't like the colors (yucky orange "stain") nor the quality.  

Some things to look out for when painting brick: stains, yellowing, cracks, mortar issues and the "reason" for wanting to paint the brick."

Install Stain Master Vinyl plank floating floors to all rooms.

I know this is a serious topic but my spirit just feels a little stained.