For only three days you might not need much but when we have our family holiday we always look for:
Included towels and bed linen (some do not always supply them)
Included heating and fire if weather likely to be cold
Wi-fi
Sky/Netflix for wet evenings in
Washing machine/Tumble dryer (probably not for three days, but after a week or two away it’s nice to not have loads of washing to do when you get back)
A nice welcome pack (tea, milk, cake etc if you’ve had a long journey to get there
Easy parking especially if going in more than one car
Depends whether you will be staying in for the evenings or just using it as a bed and a shower.