Follow some home decorator blogs(I personally like Jones Design Company, The Inspired Room, Decor8 just to name a few) those have the most information and you are getting in touch with what the market wants.Here is my REI board on pinterest.https://www.pinterest.com/nikkib123/rei-rehab-idea...Popular neutral paint colors are "Graiges" they are gray based colors.

floors in the living room are great, all the other walls are fine.that's about all that I would do, of course I would decorate it, but I can guesstimate that myself.if someone could give a ballpark that would be awesome.

In our lower end 2BR/1BA multifamily units we use mini-blinds and provide a decorative curtain rod in the living room and basic double rods in the bedrooms, for tenants to hang their own curtains.

If its an older hvac unit outside you may build a decorative lattice guard around it to hide it, paint it too.

We also like to dream and decorate. 

The apartment units are identical, while the cottages vary in color, interior décor, etc.... 

While regrouting I find myself whispering promises to the "Grand dame", telling her of how we have a friend who is preparing moulding identical to the original which will be put up next month, and assuring her that, soon, there will once again be laughing children decorating a Christmas tree in her front room window, and that maybe, just maybe, I;ll be able to convince the next people living within her protective walls to hang one of the Christmas ornaments unearthed in the deepest part of the crawl space onto that tree.Not almost, this has definitely become a spiritual experience for me.

I am great at marketing & public relations, interior decorating & staging.

Decor divas is a good company.

Interior Design is a broader subject than just decorating a living area.