Rebecca,

Podocarpus would grow fastest, and be more controllable than bamboo. Even clumping bamboo can be pesky to control!

Another alternative would be one of the acalyphas, like Louisiana Red, that makes a large shrub with great color!

jane

Variegated Hau is also a good choice for this purpose. It is fast growing, colorful, fills in fast and can be seen at several locations.

If you want to keep people out, bouganvilla makes a beautiful yet thorny hedge. With water and sun, it grows pretty fast and isn't fussy about it's soil at all. You can also start it from clippings and there's loads of other bouganvilla hedges to get clippings from.