One thing i think, is we should be investing in technology that lets us build nukes very fast. so we dont have to stock pile them all over the place, and then throw them in a mountain or bury them when they are too old. we could just stock a few, say a 2 or 3, and if we do want to use them and use more, we can build them real fast.
Having said that, nukes are kind of out of date. we have much more destructive capability if we really want to get nasty. for example, we could build a big ass impactor and put it in orbit, around venus. and if we ever need it, we just smash it in to the target of our choice at 30.000 miles an second. sure, it would be expensive to build. but would be devastating. it would release about the same energy as a nuke, it cant be shot down or intercepted, and while it would take us a while to be able to use it if we wanted to, when we did use it, it would hit so fast you would not even realize.
why am i talking so much about destruvtion and not other options, well, lets face it, a nuke is basically for pure destruction, and any replacement technology would be aimed at doing the same.