Zebra and most of the other Miscanthus varieties aren't evergreen, and have to be cut down every spring, so from spring, well into summer, you won't have much screen. There are evergreen Miiscanthus varieties, like transmorrisonensis, but it doesn't get as tall as you wish, only ~4'.

Cortaderia selloana (Pampas Grass) is evergreen, and will make a more permanent screen.

You might also consider Bamboo. There are many that will grow in your zone. Use fast-growing runners if you're using large pots, and clumpers if you're growing it in the ground. In your zone, you could have a good year-round screen in just 2-3 years.

Thanks for the info Donn. I may try the bamboo. I have to get some that gets no taller than 12' because the electrical wires are directly above. I had considered pampas grass but I do not like the sharp edges on it.

In your climate, you could also consider Phormiums, New Zealand flax. Not a true grass, but with it's strap-like evergreen leaves, makes a big, bold architectural statement and comes in a range of extremely colorful variegated forms as well as greens and bronzes. Would be very complimentary to the palms.

Be sure to check out the plant image gallery in the attached link after reading up on these possibilties.

Here is a link that might be useful: NZ flax