Personally, I got no answers myself... I suspect that this problem is more cultural than an issue of guns or not guns. There's a ton of guns in Canada, but no mass shootings. There are essentially no guns in Japan and no mass shootings. Pick your argument.
Again, I suspect that it has to do our rather unique culture. We are a country that respects human life in a microcosm (our circle where we actually live... and we talk that talk for the bigger picture). But I'm not sure that we really do respect it big picture. Our choices of entertainment (TV/Movies) are what I'm pointing to. Show some tits or folks having sex and we slap a R or NC-17 rating on it. But as long as you aren't showing brains flying around or intestines on the floor, the hero can kill/shoot/stab as many people as he wants on the way to the happy ending. And it's always been that way. Even back in the dawn of the TV/Movie age, death has been cheap on the screen especially for kids. That says a lot about us.
We are also a society that's obsessed with personal property. How many people on here even raise an eyebrow when they see a sign "Trespassers will be shot" or "Security provided by S&W" The message here is: Mess up (trespass/steal/rob) and die. I think that other places (Israel for instance) doesn't have these values and there's more of a sense of group ownership. In Canada (see Michael Moore's Bowling for Colombine... Hate the guy, but even a total asshat can make a point or two) they just don't see personal property as worth dying (or killing) for.
Anyway, just a couple of thoughts (and in no way intended to be a complete discussion). I'm generally in the crowd that is against gun control. But at the same time, it's difficult for me to see how 4 or 5 half drunk gay guys packing heat in that bar when that guy comes in is going to end well. I suspect that there would have been fewer bodies at this attack, but more over the course of a year due to accidents and petty arguments that would end in a fist fight normally...
There are no easy answers here. I can't see where a gun ban solves this problem (and I'm happy to call the people who think it would stupid). Nor do I see everybody being armed as a good solution either. I'm in Idaho, and we are free carry and anyone can carry hidden as well. Now, you may not be qualified to drive, nor able to hold down a job, but by God you can carry a gun anywhere you want (and I'm just as happy to call the folks who see this as a solution stupid as well).