You seem to have quite a few motor sports venues on your list and I'm not sure what you expect to do or see there, but to add to your list:
- Austria: Erzberg, venue of the annual Erzberg Rodeo. That's actually almost between Red Bull ring and Grüner See. For Grüner See it would actually matter when you want to go as it is a seasonal phenomenon and goes away later in summer. For the Eastern alps, there are lots of scenic roads like Stelvio, the Arlberg region, Großglockner, Passo Pordoi and Falzarego, Predil and Vrsic or lesser known passes like Sölkpass, Nassfeld, so that would be almost a week just riding up and down the mountains.
If go south from there, the whole Adriatic coast is littered with scenic seaside towns, great islands and nice backcountry riding all the way down to Montenegro or even into Albania, so there goes another week.
The next place on your list I have been to is Romania, which again would be a week on its own (Transfagarasan, the Carpathians, Sibiu and Brasov, the southern Bukovina region, Prislop pass,.. Check out the ride reports here on advrider).
Ok, I failed on the motor sports venues, but I think I gave you an idea on your schedule. Maybe make it two seperate trips and start with a southern loop and do a northern loop (Ukraine, Poland, Slovakia Czech republic,..) a year later. That way you also can keep the anticipation a little longer
I would second randel's 300km maximum recommendation per day. And I mean maximum, not average
You will need rest days, there will be a rainy day or two, you may have a few glasses of good beer or great vine that ask for a rest day (ok, that's with me at least
), you get the idea..
However, if you go, you won't regret it. It's a region full of great relaxed people, gorgeous landscapes, overwhelming history and a few racetracks here and there