I took some of the sheets, and built them, all of them took about an hour or so to score, cut, fold, and glue.
The schoolbus is a JSC designed model, and the two motoryachts and the Esslingen Townhall are from JFS Schrieber.
If you think making one of these models would be a good start for you or a young one, drop on in, spend some time cutting and pasting at the convention this October.