Wow! Its great to have access to someone who can answer our computer questions!
Heh, to a point.... I do this for work,answering questions for free on my time is not my idea of fun, but basic things like how to post forum pics I'm happy to help with! other things that require thought or troubleshooting, well that is "work" for me, and while I will do it, it is not FREE
I like the idea of the 20 long didvided. But like you said it may cause stress to the ones in the middle having other fishies on both sides of them. Maybe if there's enough space and you just put enough plant coverage to hide some/most of the dividers so they really have to look to see the other fish, not just a quick glance and be all flaring all the time.
If that doesn't work I say the 10 gallons. I think it might look a little silly imo (just my opinion) to have a bunch of smaller tanks lined up near each other. Plus I don't really like the smaller tanks anyways.