If your winter low temps are never below 20, count yourself in zone 8, not zone 7.
I don't know what you mean by "blue bamboo" and I'm assuming "black bamboo" means Phyllostachys Nigra. Most running bamboos prefer lots of sunlight but can get by fine with three hours of afternoon sunshine.
Clumping bamboos usually prefer more shade and in particular afternoon sunshine can burn them. A notable exception is Fargesia Robusta which would be an excellent choice for a clumping, non-invasive variety.

I'm finding out the nigra's are pretty expensive. What do you recommend for a nice thin running bamboo (1") that would top out at 20' ? I think i'd prefer a running as this will be a horizontal screen. Also, any ideas where to find one? The only bamboo's ive seen are at lowes and are kind of a novelty gift.

What to choose? I wouldn't know where to begin. There's a whole lotta choices and you should take your time to make a good pick. Try perusing www.bamboogarden.com for one source. There are lots of bamboo dealers online that will ship to you. After you make some choices, then scrutinize and research them to find out everything you possibly can before settling on a "winner".