BFTB - no not the islands - but probably return on a sunny day - just coast holland to dennmark
..if you get the chance get the ferry over to Wyk Auf fohr. You can also get a subsequent ferry from there to Amrum. You can also get a train over to sylt.
All 3 uslands are well worth a trip. I have been to all 3 and Fohr is my fav place. I stayed there for 2 weeks for 5 years running. The weather is changeable, but in th esummer you willget 50% bright clear blue skies, temps up to the high 20's and beaches to die for. Best place to eat is the pancake house imo.
There is a peir where you can fish for crabs and when the tide comes in the pier submerges under 2 feet of water...very cool if you are 10 years old or, as in my case, drunk!
Sylt is th eplace to go for quieter beaches, FKK stuff and expensive jewellry, although it isnt as picturesque as Fohr IMHO.
Amrun is VERY quiet...nothing much to do in the evenings, but great for couples looking to get away from humanity.
But for my money Fohr has it all, good beaches, peace and quiet if you want, nice small thatched villages like nieblum, flat, quaint harbour promenade in Wyk and stuff to do in the evening as well. Hotels and villa rentals are easy to find (but book). Goting is a good quiet FKK strand and if kite flying is your thing this place is world class!
Couple of good cycle shops on the island, swimming pool, cinema, circus etc...lot's of seals, fishing trips etc.
Sylt is th enorthern most tip of Germany so technically if anybody wants to do the German end to end they would start there I guess.