I'm up for more suggestions. I am now looking into the cts-v line of Cadillac.Out of the 2 you list, I'd take the G8.
I would go for a newer car than a 2008-2009 G8, especially considering that Pontiac is dead. I would also definitely look at other cars. Does it have to be a V8? Also, just because a car is full-size doesn't mean it is safer than an intermediate size car. There are really quite a few great choices (2012 model year) out there that you should consider. But if you've looked at a lot of 2012 cars and only the Charger R/T interests you, then if it were me I'd rather have a new 2012 Charger R/T than a 2008-2009 G8. You'll also have a new warranty with a new Charger, which you won't get with the older G8. JMO.
The new Charger is actually a pretty good car. They don't drive anything like a Crown Vic from what I've read. The only downside to them is the 5-speed auto, the gearing is very widely spaced.
I love the G8 but you can't get a new one anymore. Real shame