One thing I've notices is that spot hero has become a rip-off. I paid $42 to reserve a spot for last Friday's game at a garage about a block or so from the stadium. When I pulled in they had a sign out front advertising parking for $35 and plenty of spots available. Several other garages around the stadium were in the $30s but weren't listed on spot hero.
The best feature for Spot Hero is the no penalty last minute cancellation. I'll reserve a parking pass, then if the cash price is cheaper I cancel the Spot Hero pass. This isn't new, World Series Parking was much higher on Spot Hero than the cash prices at the lots.
Parking is the biggest obsticle to getting in and out of Nats Park without spending too much cash. Cheap seats are plentiful and you can still bring your own food. Drink a couple before walking in the door to save on drink costs. But the days of $15 parking across the street are probably gone for good. My buddy parks for free on the street, only problem is that he typlically shows us in the third or fourth inning after circling around.