Are you new to reptiles?
If yes, research first...and you might want to go with an African Fat Tail or a Leopard Gecko. Yes, they are nocturnal so as to whether or not you'll see them in the day time, it depends on the individual gecko. Both are hardy and fairly substantial in size compares to other gecko species. Fat Tails are a little mellower/more docile than leopards. Unfortunatly both species have been pawned off as "easy geckos"...As a result its quite often that new owners unintentially mistreat and mishouse their geckos because they've received misinformation about their care along the way.
Banded Geckos are fun to watch, but they're quite small little guys and have very fragile skin.
I love Knobbed-Tails and Frog-Eyed geckos but I wouldn't recommend these for someone who is inexperienced.
Never ever mix species. Its also best for most of these guys to be housed alone. They prefer it. 2 males will most likely fight to the death. A male may harrass and stress out a female...you have to deal with eggs...the female may harrass the male away from food and hide spaces...same thing with 2 females. Geckos do NOT get lonely or "need friends" -- this is a human emotion that is often incorrectly transferred to pet geckos.
There are many common misconceptions and terrible care sheets out there for all geckos. So research thoroughly, ask lots of questions, and definitely question anything a pet store tells you about species housing/feeding/etc...they are usually mortally wrong!
Try looking up some terrestrial gecko sites on Google or Yahoo!
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Too many Leos
1.0 feline "Spot"
0.1 canine "Tika"