I have been on trips with Baja Winters, Adventure and Fantasy. I would recommend them all. I would pick Adventure over Fantasy. At the time, you got a couple of more days for a few less $ and they were a little easier to deal with.
I was thinking most of the caravans stopped running the mainland trips around 8 years ago. This thread interested me, so I checked the current Adventure and Fantasy trips. Not much---mostly Baja and Copper Canyon. Not like the old days when each were running multiple trips as far south as Belize. Just checked my passport 02/25/2007 in Belize.