I would check local building codes regarding front yard hedges. In Los Angeles, the height of front yard hedges is limited to the same height as front yard fences, 3'6". That doesn't mean that people haven't built taller ones, but it is a risk if a neighbor decides to report it. Then you'll have to tear it down or try to get a variance. A variance fee is around $4800. With regards to a hedge, at least you would only have to cut it down to the permitted height.

Have you thought of a berm that is built a few feet back from the edge of your yard, with shrubs of various sizes and varieties planted (not in a straight line) on it? That avoids the fence restrictions that your city may have and the plants can grow as high as you wish. My dd did that and it is lovely and also mutes the sound of traffic going by. Min

You might also ask the Landscape Design forum about this.
Min

Nil13, had not thought of that, but it sure makes sense. Thanks for the reminder.

Min3, thank you for your suggestions. Will try LD forum, too. As for berms, I think I have one, somewhat, where the olive tree is. Were you thinking maybe higher ones and/or more interspersed?

I'm thinking a varied (hight) berm all across the front of your property but set back from the street (sidewalk?) a few feet. my dd's berm is about 3 feet high in some places and she has a few different low dense shrubs planted in front by the street and small trees and taller shrubs interspersed behind. it makes a private little yard nearer her front door, looks great and the birds love it. Min

The classic Mediterranean plant common myrtle (Myrtus communis) shears well, is tough as nails and extremely drought tolerant once established. Dark, dark green. Drawback: it is a slow grower, but that is also an advantage as maintenance is less frequently required. The foliage has a lovely fragrance.

But do check with your municipality first to see what's legal, as the previous posters recommend.

Bay Laurel is also a very nice Mediterranean choice, easy to grow, hedge, plus the benefit is using the leaves in cooking. Grows reasonably fast, drought resistant after establishing.

Another very Mediterranean option are some of the very, very lovely dwarf olive tree cultivars out there. Most are non-fruiting. A nice choice is Little Ollie Dwarf Olive by Monrovia (Olea europaea 'Montra'). It just doesn't get more Mediterranean than that. Very lovely look, pretty dense, and would look lovely with your fountain. I just love this plant, it is gorgeous, I have several on my property. Can't speak more highly of this plant. The video below says he's seen fruit, mine have never fruited, and I have TONS of olive trees on my property, many other cultivars for cross pollination opportunities.

http://www.youtube.com/watch?v=-oOlXBVrB1A

Agree with everyone to check your codes in your area, and any CC&R's you might have in your development as well.

Patty S.

I agree with everything Hoovb said about Common Myrtle and add that it comes in variegated form..Almost forgot, it has lovely scent as well.

Have you thought of Rosemary or/and white Iceberg roses? Very effective with olive trees. Stays within height limitations.

Maybe the Pittosporums? Victorian Box or P. eugenoides? I like the latter's tropical look,even if it does need some fertilizer help for chlorosis.. And even then- THAT can be a nice look of lime- yellow green.