Giant Reed, for when you really want to grow bamboo, but ...

So, giant reed spreads pretty fast, grows rather tall, has many uses,edible and otherwise,but is evidently not too hard to control, especially if it's not actually near a body of water.
I need tall, block out the sun plantings, and these might for the bill without the environmental consequences of bamboo.
They may need to be in containers, either for control or adequate moisture, but bamboo would definitely need to be kept in containers, and even then it would bear watching.
I think I will be able to get some for free, much like bamboo and a host of other challenging plants.

Be very careful here; Giant Reed may be considered and invasive species or "Noxious weed" where you live. here in the southwest, Giant reed has taken over miles of shoreline in rivers and streams, shading out native vegetation, creating food deserts for shore wildlife, and becoming an insane wildfire risk when dried out.

It's seeds are wind dispersed and can travel for miles, so controlling it will be harder than you think.

Bamboo is more controllable, and has the added benefit that the poles can bear weight and be structural (Giant Reed becomes very fragile when it dries out).

I don't mean to be pushy, but I REALLY hope you pick Bamboo.  Bougainvillea(with support structure) is also very fast growing and can shade things out (if it'll grow in your climate)

Great advice. This is why I hang out here!