Training camp Europe - any suggestions?

So, Mrs Duck will be spending a week back home with her family this summer and I'll be home alone. I was initially thinking to just take off that week and do a bit of training near my hometown. However, I now realised this might be a brilliant opportunity to plan a training camp in a nice location and focus only on training. The question is: where?

Basically, I'd be looking for a place:

1. Within a 1 day drive (say 1,200 km / 750 miles) from the Netherlands

2. With plenty of cycling opportunities, preferably without dense traffic

3. At or near a lake so I can finally nail my OWS

4. With a bit of nice overall scenery and culture

I have come up with the Salzkammergut in Austria (specifically the Attersee), which seems to satisfy all criteria. Also, I lived in Austria for a couple of years during college and it'd be nice to go back.

Does anyone have any better ideas? 

Thanks!