Planning 15 days in Chiapas: What are your recommendations?

Hello, We're planning 15 days in Chiapas. We already spent 3 weeks in the Yucatán 4 years ago. What would you recommend in Chiapas? Our idea is to rent a car so we can move around freely—there’ll be two of us. Thanks for your tips on great places to stay, restaurants, and sights to visit!