No, Ballz2, I do not have the Hogwarts Castle puzzles. What I know about them is limited to the posts I've seen on this topic and from looking at them on online shopping sites. I may be wrong, but my impression is that they make up into fairly large footprint structures, but the actual "scale" is rather small.
That said, I am sure they are adaptable to a layout, but, again, the area I have now and anticipate having later to dedicate to HP is limited, and I think Diagon Alley is the best fit with the most "play value" on my pike along with the Burrow if it is not too large.
From what I saw on the earlier posts, I am sure someone can set us both straight here.
My wife and I (mostly my wife) have also put together a 3D puzzle, ironically a Bavarian Castle that came out years ago. These Webbit Puzzles might be a little different because of the "extra" pieces Referred to in the instructions, but I am sure the process is about the same.
If D Alley goes together well, I likely will glue it to foam core or cardstock to make it more "permanent." The Bavarian Castle was displayed on a shelf at home for awhile then pulled apart and put back in the box.
Come to think of it, maybe I should try to find that old puzzle and take another look at it.