I'm going to have to disagree with everyone here.

Many of these answers would be correct if this question was asked in 1987, but it's 2017. And if in 2017 there is one place on Earth that's going to get utterly saturated with nuclear weapons, it's Murmansk in Russia.

The region around the city of Murmansk is home to the Russian Northern Fleet which not only includes most of Russia's surface ships and their nuclear weapons but also most of Russia's SSBNs, a heavy rocket depot and storage silos for large but undisclosed number of tactical and strategic nuclear weapons. Everything is just scattered enough to warrant its own weapon or two.

In the current era, no one is going to prioritize targeting silos. Why is that, you might ask? Because it's basically impossible to “sneak attack” silos. Launches from the Russian mainland are harder to initially verify but give you more lead time. Launches from subs give you less lead time but would be picked up and immediately verified by hundreds if not thousands of radars and satellites. Back in the 80’s it might have been possible for the USA to first strike the Soviets but with the qualitative and quantitative improvements to the OKO satellite in the late 80’s that window closed.

If the Russians were dumb enough (and contrary to what others may say the Russians are not dumb) to attack those silos then close to a thousand weapons would blow a 400 empty silos to hell, and the fallout would wipe out most of the east coast population centers which leads to..

Contrary to Hollywood and RAND the objective of a first strike is not total annihilation or even compete disarmament; both of those are effectively impossible. The goal is to break your enemy’s will to fight. You inflict just enough damage to make your enemy second guess their ability to “win” and begin to doubt the ability of their government to protect them. At the same time you leave their cities intact so you can hold them hostage with your second strike forces. You also leave their government alive because, duh, someone has to be alive to surrender. It comes down to this: After a first strike your enemy is going to have a shit ton of weapons left, more than enough to destroy you.

A successful first strike means you convinced him to not use those weapons.

An unsuccessful strike means he launches his first strike force at your conventional forces and second strike force. And in the case of the USA, that means we unload our use em or lose em ICBMs first while our bombers scramble.

That means smart Russians would concentrate their early attacks on bombers' bases because bombers, even with advance warning, can not escape quickly enough. The area around those bases would also be saturated in an attempt to destroy bombers that just took to the air. The other major targets would be our SSBN ports. Kings Bay and Kitsap naval bases along with their support facilities would get hit hard.