I can't advise you with plants since I have no experience in such a warm zone. But if you want to grow alpines, you will need to replace your clay. That is the total opposite of alpine soils that are very fast draining, high mineral (rock) content and low nutrition. Dwarf conifers would be a great idea. I have seen many gardens that are exclusively conifers, and they are lovely. Usually, very little soil preparation/ammending is needed.

Galcho, I also live in the northwest. Do you live in WA or OR? This will be the third year for my rock garden and I do have a few suggestions, especially for our area. Here are some pictures of my rock garden. http://pg.photos.yahoo.com/ph/judygoldfarb/album?.dir=/8ddfscd&.view=t

Make sure you have really good drainage!! I would mix your top soil with about 1/3 peat moss and 1/3 compost. Then after you plant the first group of plants, cover the top of the soil with pea gravel. I did not do that for the whole area and where there is no gravel, it is covered with moss. This year I'm going to amend my soil and put a thin layer of pea gravel all over and around the plants. The steep slope is fine, even better because there will be good water run off. Make sure you give the garden water the first two years during the dry summer months. Most, if not all, of your plants will be drought tolerant, but still need watering the first two years until they get established.

Go to some of your local nurseries (not Home Depot or Lowes) and talk to them about suggestions for your rock garden. They will take you around and show you lots of different ideas with various textures, colors and sizes to have fun with. I love my rock garden and can't wait to see how things have grown and changed this year. And, I want to keep adding cool stuff, too!

Thank you, judysgardens, i live in WA (Seattle). I liked your garden, looks very natural.
I am planning to amend my soil this summer and do some big planting in this area. I am planning to do a trip to a nursery, possible i'll find some plants that i'll like.
I see you have some grasses. Can you give me names of your grasses? I was reading labels on grasses in local nursery and could not find any that is draught tolerant and good for rock garden.

The University of British Columbia in Vancouver has a superb rock garden, in a climate that assume is likely pretty similar to yours.
Not to say one could necessarily grow all of this without effort, but here is a link to their plant list, for some ideas. (Note: This plant list is for all of the gardens, not just the E. H. Lohbrunner Alpine Garden.)

Here is a link that might be useful: UBC Plant List incl. Alpine Garden

I spent the day yesterday outside starting to clean up my beds! I can't wait to add some new plants to my rock garden!!

The 2 grasses I have so far are Mexican Feather grass and Blue Fescue. The Mexican Feather is the tall golden color and it blows in the wind. Very drought tolerant. And can grow up to 2-3ft tall. The blue fescue is also very drought tolerant.