for a totaly grown up, realy relaxing one-fly into sacramento california and pick up a rental car. drive to calistoga. book the "stress buster" package at dr. wilkinson's hot springs. you get a nice, moderate (very clean, well kept up) room as well as a mud bath, steam, hydrotherapy, blanket wrap and massage.
you just MELT (and you can walk back to your room).
they have a hot sping pool you can hop into and soak (realy nice on a cool spring nite).
you are within walking distance of some of the best restaurants the napa valley has to offer, you can take a short drive to the wineries, go to the california culinary institute, do a day trip to san francisco...
calistoga is very small (vs. napa) and also has loads of bed and breakfast geared to romantic get aways (will pack you a lunch basket to share in their vineyards, arrange a hot air ballon ride, have choc. dipped strawberries and champaign waiting in your room with the fire in the fireplace...
).
you can check on deals by doing a google search on their visitor's bureau.
bought a few of their "extra's too 
