I have done both and I am now a wagon master for Mainland caravans down there. There are lots of great places to go in Mexico, even within a days drive south of the border. I have my own favorites, it depends on what you want and how far down you want to go.
I do recommend using a caravan the first time, but many are too much of independent traveler types for that. The reliable ones are
Adventure,
Caravanas de mexico,
Fantasy,
Baja Amigos,
Baja winters.
Lots of great sources for information on the web.
1) The Mexico section of this forum
2) Facebook groups: On the road in mexico, RVing in Mexico, plus several others
3)
Mexico Rv Forums (Not a forum, but an info site)
4)
Rolling hOmes5)
On the road in Mexico6)
Kevin & RuthBaja is known as mexico light, a bit easier since you do not require a vehicle permit, but IMO not as interesting as the mainland. If you have specific questions, PM me, and I will be happy to answer them. I present seminars on the subject, so I have most of the latest info. My next one is at the RV lifestyles seminars in Kelowna BC in late June.