Above all, absolutely pristine standards of cleanliness. If it’s dusty or grimy or smelly or sticky it won’t matter how many warm scones and eggs you have left out. I don’t want to find any trace of the previous occupants (moreso now with covid).
You need to air the place really well between guests - there is nothing worse than a house that smells musty or dirty or of cooking or even worse, of cheap synthetic “air freshener”. Open all windows and doors for as many hours as possible.
As others have said, comfy king size beds are a must, with top quality white plain well-pressed cotton linen. Spare pillows. Spare blankets or throws. Plenty plain white fluffy cotton towels. A lovely cottage we stayed in had the most divine mattress topper, it felt like sleeping on a cloud and I ordered the same one when I got home. Hand soap for every sink and plenty toilet paper.
Cleaning products (including dishwasher tablets, laundry tablets, cloths and tea towels, surface spray) are much more useful to me than wine and treats, which I will buy/bring myself. And by supplying all that it makes it easier for guests to keep the place clean too.
Please let guests know upfront which (if any) shops deliver online (eg ocado) and provide the property address so they can arrange deliveries. There is nothing worse than not getting details until too close to the arrival date so it’s too late to arrange anything.
No ornaments or knick knacks - please don’t feel the need to fill empty shelves and mantelpieces as we will have lots of stuff that needs a home (books, electronics, chargers etc) and we will appreciate the space.
Wood and kindling for the fire for the first night.
Ditto for the BBQ.
I hate when leftover food products are left in the house from previous occupants. I want an empty sterile fridge and freezer. For some reason freezers often have items left in them which is yuck. Space in cupboards for food - quite often we can’t find storage and the kitchen countertops pile up with food which is annoying.
A set of keys for each adult.
Very Clear instructions for all appliances and WiFi and heating and hot water. Ideally the hot water is just always on.
Some local maps and recommendations.
I’m not bothered about quirky gadgets like fancy coffee machines that need a particular pod but good quality CLEAN kitchen equipment is essential. A simple coffee machine or cafetière will do and is less likely to be out of order.
Lots of wine glasses and drinking glasses in general!
If you do leave a welcome hamper local produce is much more special.
We often book with unique home stays and lots of the properties on their website have a lovely simple plain very neutral decor (though there are a few OTT ones on the website too), worth taking a look for ideas.