I like the Amazon tanks. Dim, brown tinged water, great looking Cichlids.

I guess if I could, I'd have one of each biotope!

Here is a link to a very cool river tank. Lots of good photos.

http://www.rivertank.com/

...and another for tank design ideas.

http://www.greenscapeinteriors.com/

There's two that I like, the first is the Amazon planted tank with driftwood and dark substrate and low lighting, just like you said.

The second is a very diverse reef that appears to be overstocked (a.k.a. on the level of about one inch of fish per tank gallon which can be accomplished safely by using large sumps). I expecialy like diversity, some snails, some sea slugs, some shrimp, some anemone's, some starfish, some urchins, some hermit crabs, some other crabs, etc... the more diversity, the more interresting it becomes.

I have to agree with Sergeant Major on the diverse reef. Nothing like a well stocked reef tank. I also like brackish biotope tanks myself.

I would love to set up a large Mangrove Swamp biotope filled with Archerfish.