Chiapas is one of the greenest areas in Mexico. It comes with amazing turquoise waterfalls, pre-hispanic ruins and the very authentic city of San Cristobal. In my opinion it's one of the completely underestimated locations in Mexico, already a famous travel destination among mexicans but still not really discovered by international tourists. Therefore it's probably one of the cheapest places you'll visit in Mexico and I think as well one of the most beautiful.
Meanwhile known all over the world, the mexican "day of the dead" is actually not a day but rather a week of celebration. In Mexico it's the most important festivity of the year and while the tradition comes from the indigineous, the day was set by the Spaniards equal to the catholic "All Saints' Day". Being in Mexico for this day was one of the most touching experiences I had during my stay and so different from what I expexted!
Baja California is one of the most popular destinations in Mexico among tourists from the United States for two main reasons: its location close to the border and its warm temperatures. Although in some parts it´s hard to avoid the masses, besides beach resorts and party destinations in the very south of the peninsula, there are as well some hidden gems. In fact, I found two of my favorite places of the country in Baja California: Valle Guadalupe in the north and Isla Espiritu Santo in the south.
Lago Chapala is the biggest lake in Mexico and as it is really warm there and you cannot see the other end of the lake, for me it felt more like the ocean (maybe as well because most lakes in Austria are really small). Lago Chapala is one of the most popular leisure time go-to places close to Guadalajara.