Setting aside Constitutional arguments for a moment, I'm of the opinion that government should be as decentralized as reasonably possible so that people can basically choose which laws they want to live under by choosing where to live (not always practical, I know).
On the other hand, certain rights that are instinctive to us should be protected universally. The rights enumerated in the Constitution definitely fit the bill, though I wish those rights had been enumerated more precisely and specifically in order to preempt attempts by "legal experts" and politicians to interpret them out of existence. They should apply everywhere in the country (and in all areas controlled by the country). These rights should also not be subject to democratic vote, since far too many people can be easily duped into voting their rights away (just look at how the "terror threat" gets people to beg for their chains to protect them).
I think it's important to keep in mind that even if we forget that the Second Amendment exists at all, we STILL have the right to bear whatever weapons are needed to ensure the balance of power lies with the people rather than government. This right comes from the simple observation that no one has a right to rule over anyone else. Ruling is a privilege, not a right.