"Democracy is the worst system of government, excepting all the others."
And honestly we won't do ourselves any favors worrying over who ends up being in charge democratically. It'll only cause what little influence we have in the area to slip, and it's not like there aren't democracies nominally allied with us doing worse.
That's really true. I don't want to see the US get involved with Egypt and Yemen in any military sense, in support of the people. My instinct is to want to see democracy born in these countries "organically", without outside intervention. Of course, America probably wouldn't have been able to become an independent democracy itself had it not been for foreign military intervention, but that was help that was asked for.
Also, I think given how hugely unpopular our military forays into the region have been, the best America can do is give vocal support, possibly a trade embargo (although that's always risky). If there are regime changes in Yemen and Egypt, the US will probably come away from that with two new allies in the region, when all is said and done. No, I don't think fundamentalists will take over either state (some good background on Yemen
here).
It's an exciting time. I really think this is America's chance to start to win back the trust of the Middle East. But more importantly, Egypt and Yemen are taking control of their destinies.