One option: Abolish Congress and the presidency. I mean, what have they done for you lately? Can you name a single good deed they've done in the past 30 years? Use some sort of board of trustees to select the Supreme Court justices and the Joint Chiefs. Perhaps this board of trustees would be selected by existing trustees, or perhaps we could use something like the Venetian lottery system ( http://unenumerated.blogspot.com/2008/03/unpredictable-elect... ).
I would welcome a government that did absolutely nothing except stop bad guys from getting into power. Unfortunately, Congress thinks its job is to pass "legislation" and it does so in vast quantities. This has piled up over the decades covering the entire country in a gray legislative goo. If abolishing Congress is too big of step, how about changing the rules so that any new law requires a 70% majority? Or maybe even a 90% majority?
I'd also note that democracy is altogether a failure at preventing the worst people from getting into power. Some of histories worst tyrants from history have come to power through party politics.
You could do worse than emulate the Republic of Venice, which lasted about 1000 years and only went down because a big empire (Austria) took them down. I would bet money that the US won't last that long, except that I don't expect to live long enough to collect.
But you could also do a lot worse than US-style democracy. See any number of lunatic 20th century dictators - and lots of monarchs. The disaster of WWI, for example, can largely be blamed on the monarchs of Germany, Austria, and Russia.
Many of these lunatic dictators were elected ( Mussolini, Hitler) and the others came to power from revolutions that promised a "people's democracy" ( the Bolsheviks, Mao, Pol Pot).
My take on the origins of World War I is quite different than yours. From my readings, the monarchs were much less willing to go to war than the politicians, and the politicians were less rabid than the mob. Britain, France, Germany, Austria, and Russia all had elected parliaments with universal manhood suffrage that voted for the war. The rise of universal suffrage in the late 1800's gave rise to a number of jingoistic newspapers and politicians. Imagine five powerful countries and all the sources of news were like Fox News - no NYTimes or NPR. That's the recipe for one of the worst wars in human history. Pre-democracy, the kings would fight a few battles and call it a day ( see the Franco-Prussian war of 1871). With a democracy, calling a truce was "giving in to the aggressor" and the war lasted four terrible years.
Luckily, the job of the government isn't to do good deeds -- it's to hold onto power in order to stop even worse people from getting it.
The purpose of democracy isn't to get the best people into power, it's to stop the worst people from getting into power.