It is pretty hard to imagine that Saudi Arabia is really concerned with having a democratic pluralistic government in Yemen with equal rights for Sunni and Shia alike.
The US does not need to get involved in any sort of nation building in Yemen, and being as Yemen is already ripped apart every which way, the only solution would be to unify Yemen under one government again.
There are the fundamentalist Sunnis and the pro Iranian Shia. High Papa Lorum and Low Poppa Hiram, it's all pretty much the same, and neither is pro American.
The main reason the previous government was pro American is because the Americans bribed them with money and weapons.
It seems the best solution is to let them all get stoned on qat and leave the US alone. Easy to do, it is a long way from Sanaa to the USA