Dave and Theresa,
We actually attended RV rallies where travel vendors had booths and showed slides of their trips. We used Fantasy RV Tours for our trip into Mexico. www.fantasyrvtours.com . Office number is 866-259-4568. You can call to get a catalog or all trips are on web site. Another outfit that does tours is Tracks to Adventure and I don't know their info off hand. There is also a group called Baja Adventures. You might check them on line as well. We were happy with Fantasy because we had such great wagon masters. In fact I am organizing a reunion of our Mexico group right before our Quartzsite rally in January. Maybe you can join us when you come to Quartzsite. There appear to be significant price differences in the trips but when you read the fine print as to what is included you will discover the value of each trip. Happy research.
Everything Betty Brewer tells you about the Copper Canyon train trip is true. My wife and I also took the Copper Canyon train trip where they put your MH on a train flat car in Mexico. It was great! Everything went perfectly. We both loved it.