My 2 cents: I think the decorating is important in that your place must stand apart from the competition in order to make an impression upon a prospective renter. If you look through the reams of VRBO listings, for example, too many rentals blend one into another because of cookie-cutter decorating. Not that they're not beautifully decorated--many are exquisite--but there's a certain sameness to them. Decorate yours just a little differently. Not in an outrageous or flamboyant or strange manner, but in a way to make your house unique so it sticks in the mind of whomever sees it. This is a tall order to accomplish because you mustn't make the house have so much personality that it appeals to only a very few, but on the other hand, a blandly decorated house generates nothing more than a "it's nice" comment and a quick flip to the next listing.
I also think a well-equipped kitchen is a must. I'm not talking about the size of the kitchen, but what's in it. Cheap plates, cutlery and glassware are a definite turnoff when you're spending good money on a vacation. It doesn't cost that much more to buy quality appointments, and the pay-off in customer satisfaction is well worth it. I wouldn't stint on the gadgets, either. It's nice to open a drawer and find enough cooking utensils, a good wine bottle opener, measuring cups and spoons, decent knives, etc. True that not everyone cooks every night, but most people do for at least some of the nights they're vacationing. Make it a pleasure to be in the kitchen when they have to, and your guests will appreciate it.