Nice report, good reading.
Have a weak spot for Friesland. Spent 3 weeks honeymooning there, exploring each and every corner. Still chuckle for the copious breakfasts.
1200 miles in 4 days is quite hefty for traversing areas so densely packed with history and sights. Do you consider to do it over at a more leisurely pace?
Have a blast in the Alps and don't forget to take ample pictures. That's good stuffing for a ride report