Not a bad idea. If they are going to stay with primaries - Do NOT let people who are not in the party vote. What right does anyone who isn't a member of a party have to decide who is the party's candidate? None. So many Democrats "crossed over" to vote for McCain - just to try and stop Bush, it was a joke.
And if we stay with primaries, get away from Super Tuesday. This risks us winding up with someone who doesn't deserve our support.
Break up the timing of the primary votes, if it's necessary to keep them.