Oh, this is right up my alley! I just finished 'Jonathan Strange & Mr Norrell' and while the fairies are less the cute, winged kind and more ancient, terrifying forces of nature, the way Clarke weaves them into an alternate Regency England is phenomenal. The gentleman with the thistledown hair is a masterclass in creating a fae being that feels genuinely alien and dangerous, pulling from older British myths where they weren't to be trifled with.
For something that dives headfirst into the folklore, 'The Stolen Child' by Keith Donohue is haunting. It’s based on the changeling myth, told from the perspective of the child taken and the changeling left behind. It’s less about a shiny magical realm and more about the melancholy, unsettling feeling of being caught between two worlds. It really stuck with me because it explores the cost of that magic, the loneliness of it.
If you want a realm that feels vast and lived-in, the 'October Daye' series by Seanan McGuire is my comfort read. Toby’s a half-fae knight detective, so you get deep dives into Faerie’s political structure, its different realms, and all sorts of creatures from various global traditions, not just European. It’s urban fantasy, so the magical realm is layered over San Francisco, but the later books journey into the deeper, wilder parts of Faerie that are pure folklore nightmare fuel in the best way.