Somewhere comfortable to sit! Should be obvious enough, but we often stayed with friends where the only really comfortable seating was the husband’s Throne, i.e. his reclining armchair.
Apart from that, a very relaxed atmosphere, no show-home perfection, where you sense that keeping everything just so is your hostess’s main concern.
And of course warm enough in winter, and on any chilly non-winter days.
Ditto to pets - to us, a friendly, waggly dog, and/or a cuddly cat, are always a bonus.
Blondiescot, we were the same when we had a dog - anyone who didn’t like her was more than welcome to stay away. Many years ago, a dd had a male student friend to stay for a few days. She didn’t tell me until after he’d left, but he didn’t like dogs, so she’d told him, ‘You’ll have to pretend to like our dog or my mum will hate you!’ ?
Something of an exaggeration, but I would certainly have altered my opinion of him!