if you are aiming luxury/high end, I have always been impressed by:
places that allow my (extremely non-feral) children to say 
properly kitted out kitchen (eg corkscrew, cheese grater, more than one chopping board, sharp knives that are sharp etc)
properly kitted out cleaning products: I don't want to have to dash off to buy dishwasher tablets, or washing powder to be able to use the washing machine (if provided - I don't stay anywhere without a dishwasher though!).
ditto for: tea towels, kitchen towel, bin bags, washing up liquid, olive oil a nice touch, salt and pepper must.
some nice soaps in the bathroom/loos are also guaranteed to impress me - not necessarily little bottles that people hoard, but just the hand soap on the basin etc.
more than one loo roll 
I have also always been touched by places that make a nice little effort - fruit in the fruit bowl, milk in the fridge. a couple of places we have been to have also provided croissants, cereal, and a bottle of wine! (these were high end city rents - say £170/night for a two bedroom place though)
things which have annoyed me are:
not enough loo roll
crappy kitchen ware - not clean enough to use, rusting, filthy oven etc
the hot water being restricted - there shoudl be enough to make sure that evey one staying can have a shower each morning. and don't restrict it to eg between 7 and 8 am!
also, if the place sleeps 4, consider having maybe 2 or 4 extra place settings/room to sit. people sometimes visit areas because friends/family are there, and we have several times catered for friends coming over one evening (admittedly, we have small children, so easier that way)