I'd rather see one nationwide primary election day, something like 120 days before the general election.
I always liked the 13-13-13-11 plan as outlined in the 2000 Republican platform.
The 13 smallest states would have their primaries the first week of March, the second 13 smallest states the first week of April, the next thirteen the first week of May, and the 11 largest states the first week of June.
No open primaries; allowing "independents" to select Republican Democrat nominees, or allowing voters in either party to cross party-lines, is like allowing the Knights of Columbus to select officers of the Kiwanis.
(If one's "independent," tough shit; if one isn't strong enough in values to make a commitment to one party or the other, well, it's one's own fault.)
No stupid caucuses; only votes of the people, not just the "activists."