Even the best windows, are still windows
Thermal curtains and double thick shades sounds awesome. What the heck at night unless you have a lighted hilltop view, do you need the blinds open?
Mi beautiful wife simply will not allow curtains. So that ends that.
Anyway we have these Levelor pleated double shades that are a decent compromise. Cheapie plastic (venetian??) blinds are terrible. Worse are those vertical things. I used to like those - good gravy, terrible. Plastic is not a bad insulator done right but unsealed just hanging thing, sure some radiant blocking ability is about it.