I really enjoy all 3 worlds. I don't think the futuristic books started out being linked to the others, but you can see the bones for it in the early ones. Same for some of the really early Amanda Quick books. But now they're all linked. She's written one trilogy with a book set in each setting. I liked all three of them. She's released 2 of 3 of the next trilogy, Quicksilver being the second and set in 19th century London.
I have been collecting the audiobooks and they're my comfort listens.