I really should have OPed the Unfunded National Debt for this thread, that's the seriously scary one..
US public debt should be viewed an private wealth and all interest payments as private income. It really represents the total savings or equity in the US economy. Deficits add net financial assets to the private sector which has helped create demand for real goods and services. This has enabled the US to maintain income growth, which in turn has allowed us to save and accrue financial assets at a far greater than would have been possible without deficits.
The only problem I have with US public debt is the provision of private wealth emanating from deficits. We can have a rational debate about this, but there's no reason to obsess over something as trivial as deficits. The US government can always honor its debt, it can never go bankrupt. US debt issuance provides individuals, firms, households and others a place to put their wealth in a risk-free form.
There's also the excess reserve drain which bonds perform, but that's another story.