I can't opine on what the cool evenings will do to taste.

However, there is a fair amount on the internet about some of the Pomegranate tastings they conduct every year at Wolfskill.

Some of the varieties that have scored highly on taste are:

Eversweet
Sirenevyi
Parfianka
VKusnyi
Sin Pepe
Azadi #0135

You can find Eversweet and Parfianka pretty easily. Some of the others are more of a challenge, but I'll bet you can find some nurseries in California that carry them.

Here are a couple of links on those tastings:

http://www.edvaldivia.com/gallery2/main.php?g2_itemId=535

http://www.edvaldivia.com/gallery2/main.php?g2_itemId=332

Richard Ashton has a pretty good book out on Pomegranites if you are interested

Here is a link that might be useful: dallasfruitgrower

Thanks for the links and book recommendation. The links were very helpful. Yes I can get Eversweet and Parfianka but the others are harder to find. Thanks. Linda