Unfortunately suite hotels are usually outrageously expensive

Not really in my experience. For example, Marriott's suite brands are often cheaper than their more upscale standard hotel room brands.

This might be an option in a lot of downtown areas but not on the outskirts of London (the hotels are mostly airport / motel types) or in the middle of nowhere in Scotland where 4 of my sister's previous Airbnb rentals have been.

Her last one was incredible. A lovely little 3 bed home with a hot tub in the garden room.

I had to visit my employer in Ottawa (I live in the UK). They booked me into a suite hotel, because there was an international conference in town, and all the smaller rooms were booked.

So I got a huge TV, a kitchenette, a double bedroom with another huge TV, a bathroom with his-and-hers basins, and a single bedroom. The next morning I discovered a second bathroom, like the first; and a utility room with a washer and a dryer.

The problem was they didn't have a bar, so I couldn't get a bottle of wine. But not a big problem; the suite hotel shared a lift with the regular hotel next door. So I would ring the barman at the regular hotel, and he'd meet me on the second floor with my wine.

The suite hotels in the US often don't have a bar and limited or no food service at night. Though there are exceptions. (Marriott has been upscaling Residence Inn in many cases--probably because they have so many suite brands after acquiring Sheraton.)