My recommendation would be a bearded dragon. They are medium size lizards that typically reach about 18 inches long, although the rare individual will reach 2 feet. They are hardy and make good beginner lizards. They eat crickets and mixed greens and vegetables. They need at least a 40 gallon tank as adults, with a basking spot that reaches 95-105 degrees and UV light.
They are also very tame and tolerant of handling. My bearded dragon is content to sit on my shoulder for extended periods, he also likes to run around and explore. Very docile, good eater, never bit me.
Although they're a bit smaller then what you specified, do your research and you'll find that they might be a good lizard for you.
