Originally Posted by Frostback
BMW Motorrad will rent me a GS800 for 160 Euros per day with a 700 km per day max.
The fee IS high. But, it's pretty much average - maybe even a bit low for a major rental agency. Compare with Moto Mader and Moto Center Thun in Switzerland and BiancoBlu in Italy for sample rates. I've heard that Moto Greek in Munich has low rates, but I'm not sure how much traveling you want to do to get to the rental agency.
700kms/day is quite generous. Riding the pass roads and secondary roads you'll be hard pressed to do more than 400kms/day, assuming stops for photos, eating and the occasional piss - 250 - 300 seems to be about average.
Mid April WILL be dicey. Most, if not all, of the high roads will be closed.
I'd head for Italy and the Dolomites. Absolutely spectacular and, as the area is a major tourist spot year round, the roads WILL be open (barring the occasional fresh snowfall). Also, the Italian side of the Alps tends to be a bit warmer and sunnier.
And another plus for alpineroads.com. Tim, one of the moderators, lives in Austria.