I've been tasked with finding a birthday trip for my wife and friends (6-10 women)....one of those zero on the end birthdays. One thought was a spa type resort in the California wine country, something fun not stuffy as they all like wine (oh, there's a surprise) and spas.

Trip would be November-ish.

Any suggestions would be appreciated....

I have friends that have gotten together and rented houses in the wine country. That might be a good alternative.

This website is an example. Look at the rentals, some have spas. http://winecountryrentals.com/

This might give you more bang for your buck.

Check under California and scroll down a ways and you will find a number of threads on Napa/Sonoma/Wine Country, etc.

And even if you don't stay in Calistoga (north end of the Valley) - you or the lases might enjoy the Mud Baths.

http://www.calistogaspas.com/

Look at the website for Indian Springs Resort in Calistogo. It's a peaceful getaway in the wine country that has a huge natural hot mineral pool, mud baths, a complete spa, and charming cottages to rent with full kitchens and living rooms. My wife LOVES this place. Be aware, the wine country can be cold in November.

You don't give a budget and there are so many places to go - I'll just mention Kenwood Inn & Spa in Sonoma as a possibility on the higher end. I think it would be perfect for a group of friends because it is a small and beautiful resort with a great spa and centrally located near Sonoma and other places for wine tastings/etc. When we lived in the Bay Area, it was one of our favorite spots to go for a "recharge" weekend. Breakfast is included with the room and they have a wine bar and small but good restaurant so the group doesn't even need to leave the property!

Another vote for the fabulous Kenwood Inn and Spa. It is lovely, restful and romantic - so it may not be what your wife has in mind for a lively group of women.
The Carneros Inn does have an incredible spa facility, and it may provide more of an accommodation variety. These are both higher-end properties.
There are quite a few spas in Wine Country at a variety of price ranges.

Kenwood or Indian Springs for the spa. DW likes Indian Springs becasue you can also enjoy Calistoga when not in the spa.

I recently did a wine country trip with friends for my big Xo. We all stayed in a home in Sonoma -- loved it as we were all totally relaxed and didn't have to put on a show (or makeup) like in a hotel. The folks at beautiful-places.com found me the house and created lots of fun activities for us to do...and stocked the house with lots of goodies....and filled my room with balloons as an added surprise.