I don't think you 'murricans need to make reservations for a factory tour, but I heard they changed quite a bit on tour-planning, so better be safe than sorry...
This is the phone# you should call for the factory tour:
(+49)7119115384
Here's info for a hotel in downtown Stuttgart:
Hotel Dieter. In de Brennerstr. (+49) 7112599379.
60 euro a night, ex. breakfast (better to have breakfast in town)
(I haven't been to this hotel myself, so don't blame me if it's crappy
)
Or ask the people at Porsche for hotel recommendations.
There is a nice hotel at walking distance from the factory
When you're there and if the tour doesn't include it, don't forget to visit Werk 1 (across the road), this is the old factory building where you'll find the exclusive department and the service department for "special customers" (where they service and restore all the rare cars).
If they give you a hard time at the gate, tell them that you are there for "Ersatzteile" (replacement parts)
If you go to Stuttgart, you could also visit the Mercedes museum in Untertürkheim (it's really close)
You could also visit:
Gemballa in Leonberg. Mollenbachstr 17
Techart in Leonberg Röntgenstr 47
(Leonberg is about 10 miles from Stuttgart)
Try contacting Ruf as well.
I've never been there myself, but I hear they're nice to visitors.
If you have an idea when, let me know and I will see if there are any big events that would be fun.
You might also like to drive up to Gmund, where it all started. The old factory there is now a private musuem. The drive up there is supposed to be very nice (and it is the road that Porsche used as their "test track")
Lemme know if I can help you out on anything...
cheers,
Jeroen
ps A stop in the Netherlands is mandatory ofcourse