That new raft design is pretty neat! Man... This tank is really giving me ideas. Saw a super squat rounded corner square glass rimless at the LFS that would just be perfect for this open top type setup. If only I had a place to put it. Did you have to stick to more terrestrial plants given the lower humidity in this setup compared to your others?
Yes short and broad tanks are perfect for this kind of setup. Tanks with that shape can offer a great view down to the water's surface and with plants growing up and out of the top you get a real nice effect similar to a garden pond.
The plants in this tank are all semi-aquatic marginal aquatic plants, but they can handle lower air humidities just fine. The only plants that I have used in ripariums that need very high humidities (and closed canopies) are crypts, anubias and Java fern. All the other ones that I have tried do just fine in open-top tanks.
I got back to replanting this thing tonight. I think that I have a pretty good result. It still looks a bit disheveled, but it should perk up as stuff grows in.

There are several new plants in there. The Cyperus umbrella sedge over there on the left is C. albostriatus/I] and it is shorter (~8") than the other one (C. alternifolius) that it replaced.