I am not sure what geckos you are planning to get but the size sounds about right.
The enclosures I use are featured in a care sheet on the Herp Shop web site. I am very happy with them... well I sold one a while back and kept the one which sits beside my computer at home.
Visit
http://herpshop.com.au, click the links and care sheets button, and then the Gecko Enclosure.
I have seen knob tailed geckos in glass sided enclosures without a lid. They were obviously doing pretty well.
Perhaps is it time for a thread titled "Show us your gecko enclosures".
Our female Cilarus is looking pretty gravid at the moment so our fingers are crossed.
