I believe that the standard server type will have RvR areas in each zone, but areas outside of that will be designated for PvE content, and any RvR in those areas would need to be consensual.
I'd assume that there will be a 'pure' RvR style, as well, where any areas would be RvR enabled, but that's just a guess. There will probably be RP flavors of those, too.
I can say, though, that when higher leveled players enter a low level RvR area they are turned into chickens (braaaaawk!), so high level ganking won't be a problem.
I'd tend to favor a standard server, too. I'm all for RvR, and plan to partake heartily, but sometimes it's nice to just be able to kick back and PvE for a bit without having to look over your shoulder constantly.