Well, based on my research, the Carnival Spirit is offering four, five, six, seven, eight and nine night cruises to the northern Mexican Riviera beginning December 6, 2010. Prior to that the Carnival Spirit is doing eight night cruises to the southern Mexican Riviera.
So, with the new itineraries Carnival will save some fuel (by not going all the way down to Acapulco) and will allow passengers to pick any cruise length between four and nine nights.
Four nights - two days at sea and one day in Cabo
Five nights - two days at sea and two days in Cabo
Six nights - two days at sea, two days in Cabo and one day in Ensenada
Seven nights - three days at sea, one day each in Cabo, La Paz and Mazatlan
Eight nights - three days at sea, one day each in La Paz and Mazatlan and two days in Cabo
Nine nights - three days at sea and either one day each in La Paz, Mazatlan, PV, Cabo & Ensenada OR one day each in La Paz, Mazatlan, PV & two days in Cabo
Looks like Cabo comes out the big winner with these new itineraries. I guess I'll be on one of the last cruises to Acapulco in November. But I'll likely come back for one of those itineraries going to La Paz.