We stayed in a wondeful cottage last year that had loads of thoughful touches.
Tea tray set with tea things and a locally made cake, milk in the fridge, cleaning supplies, including a few dishwasher tablets and washing up liquid.
Sharp knives and nice cooking equipment, decent pans/graters etc. Lovely linen including tablecloths.
Beautifully furnished in a not too precious way with some new/some older furniture. Fresh flowers from the garden in all main rooms.
Bookcase full of books, piles of toys , books and games for the children in their room and the main living space, including buckets and spades outside the back door for going to the beach.
Small outside garden for the cottage only, with a furniture set, small patch of lawn, and some pretty but robust planting.
Extra touches like bedside rugs, a dressing table in the main bedroom with extra lighting, a hairdryer etc. Storage space to put away suitcases/luggage, once we had unpacked.
One additional thing that I would love in holiday cottages is decent curtains/blinds that actually block the light out, especially in children's rooms.