The Chase format has some advantages, but it needs tweaking. This year for example, Stewart is basically making a mockery of it by winning 3 out of 8 Chase races so far.
I would make two changes. One, the premium for actually winning a race should be higher, much higher. Fans hate to see drivers protecting their position at the end of a race. Make winning worth something.
Two, I would give a "wild card" entry into the Chase for any driver who wins a race during the Chase portion of the season. They would go into the Chase in 11th place, say 10 points below the 10th place Chaser. This would give the non-Chasers a big incentive, and would also give the Chasers an incentive to go for the win to keep hot cars like the 20 out of the Chase.