Motels and Airbnb

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So thinking of binning off our dec trip to wdw as I’m not feeling the love for it, with all the new charges and less for the money, so thinking west coast, my husband has wanted to do this for years, but haven’t a clue on how to plan it properly and don’t want to be tied staying somewhere longer than we need, can you just rock up to motels over there or is it a bit dodgy, have had a quick look at hotel prices in SFran but I didn’t realise how expensive they could be, also is air b&b still a thing or is it illegal and not worth the risk of booking a few different places, any advice gratefully received