My parents owned a vacation condo for many years in Myrtle Beach, SC. They always said the same thing, don't plan on the rental $ to pay for it (probably obvious, but it can't hurt to reiterate it).
Mostly, I just wanted to post a little tidbit about a nice thing to do. My parents put a little journal in the condo and invited people (renters, family, whomever was staying there) to write in it. This was a nice personal thing for the renters to list comments/suggestions/cute vacation stories. It was also nice for my parents as the owners to get some feedback and tips. Also, this helped them figure out that the rental agency they were using were less-than-honest (to be P.C. about it) about how often it was rented. It turns out that a family had rented it, written in the journal, but that the rental agency DID NOT tell my parents that it had been rented!! God only knows how often they did this before they were found out. So, this is another vote to handle the rentals on your own.
I also agree about personal touches ... wine glasses, DVD Player with a small selection of DVDs, multiple TVs, are all nice things to have.
Good luck!!