Rosemary is grown a lot, and many of the grey-leaved plants - lavender, artemesia, santolina, sage, plus herbs like oregano, parsley, different kinds of thyme, scented geraniums grow all over the Mediterranean area.

Mitzy,the first thing you are going to have to do is really work on the soil. To be able to have many of these types of plants grow and survive in your garden, you need to create incredibly well draining soil that is not particularly rich. Many of the plants you'd want to incorporate can not survive very well in humidity, even the "like" plants you mention. The way to get longetivity is to really go after the soil. janen mentions many fine plants. Santolinas are gorgeous, but they are not all that long lived (I've had one for 3 years, which is the longest I have had one to keep relatively neat and not die out). You are very limited on good lavenders. Try the spanish type. There are many available from specialty herb mail orders, but the variety locally is slim.
How about yucca? Try non-trunking ornamental yuccas for a great spikey effect. I love the gold leaf yucca next to a lovely grey leaf plant like silver germander.
For more ideas, bulbs etc. go here: http://www.mediterraneangardensociety.org/
There are some interesting articles if you search through the pages..

Good luck, and have fun! My neighbour has a mediterranean style garden between the sidewalk and the road. It's a bit wild, but it is just lovely.

GGG

Good for you for choosing plants that flourish rather than trying to help true mediterraneans struggle.
Here are some I grow that might be good substitutes:

Bath's pink is a good choice. I have it growing where it can tumble over rocks on a slope.
Rose campion is a good grey plant, if you don't like the magenta blossoms, snip off the bloom stalks when they appear.
Bulbine is a good Texas native that grows here, it looks like a skinny aloe.
Kniphofia -- "Red Hot Poker"

Salvias are my fav. S. leucantha makes a good substitute for lavender effect. Not many blossoms in the early spring, but late fall is a marvelous show until frost. Pineapple sage and S. coccinea are good reds. The salvias attract butterflies as an added bonus.

From the plant list in the link that GGG offered, here are the plants that I grow:

Eschscholzia californica, the California Poppy

Hermodactylus tuberous

Iris

Oaks

Osteospermum - Cape Daisy (Ice Plant)

Punica granatum, the Pomegranate

Rosemary

Sisyrinchium

Vitex agnus-castus - Chaste Tree, Monk's Pepper

Nell

Here is a link that might be useful: Salvia leucantha and Friends

Can't help you with the other stuff but I as far as trees go the Italian cypress, mugo pine and Cedar of Lebanon come to mind. All pretty easy to find w/in an hour of where you are.

Thank you all so much! I will get started planning right away. I have some asparagus like fens in a bed off my sidewalk and road with some creeping phlox (hot pink) and a large accent rock...all randomly planted. It did very well over the droughted summer and looked like it was a bed from greece or something. Last year I planted glads (multicolor, 2-3 foot ones with large spikes, not the smaller ones) in a mass, I received so many complements on them, though that was my random planting for the year, not mediterranean. I have been to the medeterranean garden society website before and found it hard to navegate the site. I will try again and see what I can dig up! Thanks!!!!

I have some potted citrus trees that I take in for a few months in the winter. Also, Athens has both the State Botanical Gardens and the nation's oldest garden club (so the plaque says). The Botanical Garden has a Mediterranean section.

Here is a link that might be useful: State Botanical Garden