I met my girlfriend when on her first ski trip, where she was told to make some big S's by her sort of skier friends. that was it for instruction. No goggles, no ski socks, must've been uncomfortable as hell.
It took me almost two years to get her back on the hill, but now she's been a season pass holder at three different mountains over 4 years. Have gone to Loveland, Copper, Sugarbush and some smaller hills with her. Taking her to Jay for the first time in exactly a month. I guess what I'm saying is, I succeeded and I hope you do too.
I would take her to a small local place pre-trip for her first lesson. Go on a weekday with nice weather. Keep it relaxed. Do it as sort of "get ready for our trip" session.
My gf really only wanted to learn from me, which is highly advised against by pretty much everyone, but it worked for us. I am trying to convince her to take a more advanced lesson now, but she isn't interested(for the record she can carve, ski switch and even do some trees now). I even offered to take a lesson too at the same time (I mean we all could use one). So judge the teach her yourself vs. take a lesson question for yourself, taking both of your personalities into account, but in most cases pro lessons are the way to go.
The important thing on the first few times out is making it comfortable, enjoyable and fun. Get her some decent software (if thats the right term), a good hat, good goggles, socks, base layers, decent coat and pants etc. Can make a huge difference in enjoyment. Go in for a few beers when she gets cold. Avoid crowded obnoxious ski areas (read: Killington). If on the EC I'm thinking Burke, Sugarbush, maybe Iceface because of the cool town, but it does get awful cold there. jay is probably too isolated. West, I'll have to give it more thought, but Aspen or some of the Tahoe areas seem like a good idea.
Basically show her how fun skiing can be, don't make it a challenge unless she is the uber-competitive type, in which case make it a beatable challenge, not a frustrating one.
Go with her to get rentals, teach her boot buckling techniques, make sure her pants aren't tucked in, basically don't let her be a gaper. She will thank you for it later. try to do all of this without being condescending.
Your dead on with the spa/dinner/fireplace ideas. think of other little things like that to work in. Fancy chocolates and some peppermint schnapps out on the hill doesn't hurt either.
At the risk of being repetitive, make it a fun way to spend time together.
good luck and don't screw this up!