Her are some recommendations of where to travel and stay in Mexico
Mexico City – I think any trip should start or end there, I have another post dedicated to Mexico City
Mexico is a big country, it is about the size of Europe and will be hard to cover it in a single trip. Even most Mexicans haven’t visited all it’s states. I will say that it all depends on what you like and how long you have to decide where to start and what to cover. The map below shows what I would consider the best destinations, but of course there are many more places to explore than these. The google map at the end of this blog has also some routes that could help you plan your trip. I will describe them from north to south, as I can’t think one area is best that the other.
Baja California Norte
Baja Norte – You might have heard of Tijuana, I haven’t visited it , so I can’t say much, but it is is an interesting city where the US and Mexican culture meet. I wouldn’t stay long and is not as dangerous as people say. But it is easy to get there as the airport is well connected and it is in the border with San Diego. Most likely you will start your trip there and ideally rent a car or get in tour to explore the rest fo the state.
Perhaps the best area to explore is around Ensenada an area called Valle de Guadalupe, where you will find a lot of vineyards that offer wine tasting, accommodation and great food. You can also explore the coastal towns where you will find fresh seafood in very relaxed environments
Heading further south you can explore Cave prehistoric paintings , they are a bit remote, but worth visiting. Here is a website with some information. If you head into the Golf of Cortes, you will find small towns with beautiful beaches worth exploring a few of them. Finally you can head down to explore further south the peninsula or return to Tijuana through Mexicali and Tecate.
Baja California Sur
I have another post that shows you an itinerary and some pictures
Riviera Nayarit and Puerto Vallarta
You can find more info here:
Map with some suggested itineraries
Here is a map that shows several itineraries and areas to visit. It includes Guatemala as well