Being a landlord is a business and having compassion for individual tenants life issues is not a luxury you can afford.

They are now thrilled to have a luxurious shower and I am giddy that the value of my place went up :)

I do not have the luxury of flying to FL to sign a lease in person.

Here is what I would do if it were my rental (complete with granular details) assuming this is not a luxury rental and you are just looking for fair "rental condition" and some low cost wow factor (or at least some "ok decent" factor)....First I would pull the knobs and TSP (I like the powder mixed with water) the cabinets and use the abrasive side of a Scotch Brite sponge--just dip it in the TSP (and hotter water cuts the kitchen greases)... 

B/c they are so small, you do some very luxurious designs and finishing and charge a premium for the space.  

I did not have the luxury of buying regular single family homes with little profit for many years and waiting for them to be paid off.So I came up with a better way.  

When we find them, we want to keep them.If we were renting luxury apartments and homes in the A market to A tenants, as @Elizabeth Colegrove is doing, the market response would be different.  

Since we had built it out ourselves we had the luxury of making it handicap accessible all on one level. 

In CA anyway, there is a huge luxury tax on short term rentals, less than 30 days. 

To a certain extent, I recognize that this can be a function of the environment of the rental and the market for which you're aiming - obviously a luxury unit will not have a $350 refrigerator.