I may be misunderstanding, but am I right in assuming you were only thinking of more than one critter because you thought they'd want 'company'?
has put things right for you - in fact very few reptiles are truly social in the way that many mammals are - a viv of the size you said would be great for loads of possible lizards.
As you're attracted to the geckos, a Leopard Gecko would do very well on it's own in that size viv. They are easy to get, tame and keep.
African Fat Tails are even nicer! Very slightly smaller (only by a very small amount), just as easy to keep and even easier to tame. A little harder to get though.
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and come out with a leo and set up in about 10 minutes (not that I suggest you do that - the viv should be up and running for a while to make sure the temps etc are okay before putting anything in it). A fatty will take a bit more effort.
If I did misunderstand you and you definitely want more of a 'community' of geckos, then maybe look at the Stenos. They do well in a small group. Their tiny size makes them less appropriate for a lot of handling though. Less of a personal pet.