I very much prefer to look at earlier models as base for my fantasy: beginning with the nascent civilizations of Sumer and Egypt, up to late antiquity and migrations era. As far as mixing fantasy with "advanced" technology goes, I'd much rather go for something gonzo-futuristic (ray guns! jetpacks! giant robots!) or really weird and decidedly unrealistic stuff, rather than any kind of imitation of actual post-medieval tech. I find steam engines and muskets to be boring and ugly.