I am currently breeding my pair of P. laticauda (gold dust days) and would be great for someone starting out in days. They are so easy to keep. I am keeping mine in a much larger tank then they need (3'l 2'h 2'd) and will be moving them to a smaller tank as soon as i am completely sure breeding is over. I recently found some hatchlings, the first since august!! A tank size of 2' high, 2' wide and 18" deep should be ample room for a pair. You could probably go smaller.
My first day gecko though was a P. m. grandis (giant day gecko) and he was just as easy to keep. I'd recommend both of these for a first day gecko. The only thing i have against the gold dusts compared to the giant day is that i hardly see them. Though i know this is due to the large tank they are in. So many places to hide. And they are way more shy then the giant day. I dont know if mine was just used to people, or most giant day geckos are 'brave' but he would happily sit on the front glass all day whereas my gold dusts dont go near it.
This is just my experience though. Good luck with whatever species you decide on.
Claire