Interested in a different lizard species

Hello! For the past year and a half I have been keeping leopard geckos. I really enjoy them, I have handled them all to the point where they are familiar and comfortable with me taking them out to relax for a while. I think they're a great lizard and I'm excited about owning many more and breeding them in the future!

Right now I am on my way to moving them into a rack system to conserve space as well as have room for hatchlings if I get any these season. When I move them into the rack, I will have two empty tanks that I'm looking to eventually fill. I'm looking to either make them into display tanks for my leos or to house a different species of lizard, as I am not allowed to have snakes at the moment.

These tanks are 32" long, 15" wide, and 16" tall and are made out of melamine with a glass bottom. They comfortably fit two adult female leopard geckos in them. I have been looking into different kinds of skinks and I'm interested in adding a skink to my little collection. I really love Blue Tongue Skinks but know that these tanks aren't large enough for a full grown adult to live comfortably in one. If I were to go with a skink, what kind should I get?

What I'm looking for...
Price Range: Up to $200 for the animal.
Temperament: Easy to tame, something I can handle several times a week or something that will relax with me while watching TV/on the computer. A temperament like a leopard gecko would be awesome.
Size: A single animal that will fit comfortably within one tank or a pair of animals (two females maybe?) that won't mind being housed together. I am not looking to breed these animals so a male x female pair would not do and I know most male x male pairs will fight.

I would like to put time and effort into making this tank a nice display as well. Right now neither of them are fitted with a light, they have UTHs with a thermostat but I am willing to put a light in there. If you don't think a skink would be good could you recommend me a different kind of lizard?

Thank you!