The only thing I worry about with both those species is their heat sensitivity. If your school is anything like the ones in my town, the A/C and heat are run as little as possible to save money. While all the lizards you currently have could tolerate temporary temperature swings, Crested and Gargoyle Geckos begin to experience heat stress at ambient temperatures above 80 F. One hot weekend with the A/C turned off could spell major trouble.
I don't have many species recommendations, as you already have the species I think of as being the hardiest. If your students like the Leopard Gecko, you could look at an African Fat Tail Gecko. Day geckos and anoles are extremely interesting in a communal terrarium setup, but the heat, light, and humidity requirements get more complicated.