DTM at the Ring is crowded, book your tickets in advance.
Best seats in the House : T4a or T3.  
Races are short, but on short track layouts so you see the cars quite a lot.  Most of the time a good fight on track, even more when Ullrich shouts to "take him out"  

.  Chris24 went to DTM last year, he might be able to give you some good advice.