3 comments.
Webmoose:
1: Bettas and Gouramis are not good tankmates. I've seen dozens of threads complaining about this in the past, and know gouramis to be territorial (mostly to conspecifics, but sometimes to other fish if the same size). It's an idea many ppl have, but one you'd best steer clear of!!
2: A good low pH for these guys would be 6.5. Most cories like the 6 range, as do neons. Cardinals prefer even lower pH... 4.6-6.5 or so!!! 6.5 is a good compromise for all these fish, and I think you'll find the driftwood will naturally lower the pH. I've noticed that all these fish can survive in nautral pH if they've grown up in it at a breeder's or if they've been sufficiently well acclimated by dealers/retailers. I'd still provide them with a more natural environment...
Cage, Raven and Moose:
3: It's true that many fish swim back and forth. Some species love to swim up and down, though. Zebra danios certainly do, and my neons always move up and down my tank. What's great about the driftwood idea is that these fish will all pick at the wood, looking for small scraps of food. As a result, they'll move up and down it. Ooh, and think how great that wood would be for a couple of dwarf plecos. Also, if you're concerned about the impracticality of a high tank, think seriously about layering fish. Get bottom feeders, middle feeders and surface feeders. Good examples of each follow:
Bottom: All loaches, esp. Kuhli loaches, Yoyo Loaches, Angelicus Loaches. All corydoras (Cory) cats.
Middle: Neons, cardinals. Most fish, really. You're set, though.
Upper: Zebra Danios, *Hatchetfish* (Marble Hatchets are the easiest, and are THE quintessential example of a surface fish), many gouramis.
Of course, cleaning a hex is a little harder... All in all a little less practical. But think how rewarding it is as a showpiece!!
P.S. Hehe. You're giving me relative numbers... How modest! the 55s at my
LFS are only $50. Are you talking about acryllic tanks? I'd say go with the Hex if it's under $100. I think the glass hex tanks usually go for about $130-$160. Just a vague approximation, though.