You can visit Mexico all year long. Even the rainy season (May to October) is not a real turning point in the journey. Short, intense rain showers in the afternoon and evening hours are not associated with any significant temperature fall.
In the north of the country (Baja California and Copper Canyon), it is very dry in the winter months, fresh and tender in the night.
Mexico is a country of the 1000 worlds and can be visited and seen in many variations:
A large number of operators offers a wide range of products; these kinds of trips can be distinguished:
Flexible rental car throughout Mexico. The road conditions (especially the toll roads) are in (very) good conditions and you can feel safe along the tourist route.
Guided small groups have the advantage of the group in a familiar atmosphere.
You are not a group person, but still want a tour guide? A private tour guide is the solution. This kind of tours may-or may not come with elegant accommodations. Eg. haciendas are designed to be a luxury travel.
For small budgets and those seeking for adventure, a journey by public bus and shuttle tours is an interesting alternative. Travel to and with people, so to speak.
No matter the way you want to experience Mexico, the country of the 1000 worlds will exceed your expectations!