Sounds like a good plan!
My tank is similar but on a smaller scale (13x13x17). I've got a heater in the water set on 74 and it does a great job of bringing the temperature up plus the water helps add humidity. It's setup under the eggcrate. The canopy I built has a screened lid but it's mostly covered with a piece of plexiglass I cut to fit.
I would definitely go for the night light. When I built my canopy I put two bulb sockets on my canopy and I have to say we thoroughly enjoy watching them in the evening. It's just a standard aquarium 15 watt bulb I got at Wal-Mart (the long ones). The other socket holds a 13 watt fluorescent bulb for daylight.
As far as hiding places, they'll hide wherever is available but they do prefer the high leaves. Mine usually stay up on the big leaves near the top where they overlap each other. One of my girls though prefers under a rock.
They do seem to like the large water area so I highly recommend having some sort of water feature beyond just a bowl. Something to think about.
Here's a link to my recent rebuild and a link to some before photos.
10 Gallon Rebuild!
My 10 Gallon Tree Frog Tank
Have fun with it and keep us posted!