Five Reasons Not to Leave the Beach in Mexico

You're interested in Mexico as scenery, not as a place with its own history and variety
Avoid my adopted city, Guanajuato, or the nearby city, Dolores Hidalgo, both intimately involved with the initial struggle for independence. Avoid the steps of the Alhondiga, don't even think of going in, where you can learn about the slaughter of the Spanish and see the mural by Jose Chavez Morado, who combined his passion for painting with his concern for social justice.

You are a seafood lover and have no idea seafood is available in the center of Mexico
First of all, I'll admit we eat thawed flash-frozen shrimp and fish then steeped in lemon used to make ceviche tostadas. But they are tasty, probably cheaper than at resort areas, and worth a try if you are an adventurous traveler. Yes, I was sick once, but only for an hour or two and I'd eaten on a hot afternoon in an unfamiliar market. You can behave more wisely.

Walking is your least favorite activity
It is much easier to lie on the beach than walk up hilly lanes or from square to square. But do really want to return home a couch potato? And these days, most cities tourists visit have an abundant supply of cafes and restaurants where visitors and local people enjoy sitting over a cool agua fresca or a stimulating cup of café americano. In Queretaro, you can experience colonial Mexico without walking up a hill at all.

You don't want to know any Mexicans besides waiters and maids and you certainly didn't come to meet Americans
Let's face it, both the local and local-by-adoption folks, can give depth to your visit and provide stories for you to tell back home. If you visit any of the university cities during term time, you're bound to bump into students, night or day. If you're fifty or over, with a little enterprise you can stop a North American looking person on the street and find out all sorts of information about the city you're visiting. If you're in between, in my city, try loafing a while in Plaza San Fernando or the most social plaza, known as the Jardin, between 5 and 7 in the evening.

A vacation package is soooo much simpler
Touring away from the beaches is becoming gentrified, meaning more B &Bs and other cosy comforts, but if your goal is purely rest and recreation, then a vacation package has its merits. On the other hand, you may find cooler weather at the higher altitudes.

You know very little Spanish
Maybe this is the best reason for staying in a resort area. Life will be simpler where the staff is likely to know some English. But if you would still like to see another part of Mexico, try San Miguel de Allende, almost at Mexico's center and accessible from the Leon/Guanajuato International Airport or Ajijic, accessible from the similar airport at Guadalajara. Both places are English-language colonies but still retain a Mexican feel. If you do want to learn more Spanish, cities like Morelia, Guanajuato, Guadalajara and San Miguel de Allende make good destinations for people who would like to live with a local family and attend a language school, sightseeing mainly on the weekends.