Leif's toungue-in-cheek response is spot on. A tank that size is fantastic(and looks great too), but as you are well aware, retics are quite small. I'd suggest making a much smaller tank, say half the capacity, so that you might actually observe more than fleeting glimpses of these guys.
I also purchased my retics from Sean and have mine in a big pretzel jar, about 3 gallons. Its heavily planted and I rarely see them--I couldn't imagine finding them in a 40gal tank! I also have some ventrimaculatus in a 30 gal hex and also wish I would have down-scaled that tank as well...the frogs are happy, I'm sure, but I want to observe them often!
To each his own, and congrats with your new guys.
Scott
-----
Scott Menigoz
Phelsuma: grandis, kochi, standingi, laticauda, v-nigra, mad mads and klemmeri
PDFs: azureus, citronella, alanis, terribilis, green& black auratus, cobalts, patricia, regina, leucomela, vents, Brazillian yellowheads, reticulatus and galactonotus
Over 100 Tads/young frogs of azureus, alanis and cobalts