Spa and Ring combined trip would be advisable if you are making the journey
Well as it is somewhat my home ground, I would at least be present if for one of them as my schedule permits. Me actually driving depends on what happens in the coming months, at the moment way to much non-alfa related but cool/interesting stuff going on.
But what are Alfa Classico race days....
I think there are several interesting events to visit.
One of the best with alfa and spa together is the "myalfa trackday" on spa.
To get an idea
http://youtu.be/n6mwH5dlJQU
http://www.myalfa.eu is a parts supplier which does ones a year this trackday.
An other good time would be when the dutch alfa romeo challange visits spa.
But for both the calender is still open for 2014
Ring visit is interesting when a VLN race held on saturday and public driving on a sunday.