Spa treatments are a great idea. Facial, massage, manicure/pedicure, the works. I've met very few women who wouldn't love to be pampered for a day.
Also, even if she isn't a big jewlery girl (I'm not), she may still appreciate a ring. One that really shows you know her tastes that she could wear all the time. Doesn't have to be an 'engagement' ring. If she is really an intelligent type she should understand an 'I love you' ring without a lifetime commitment.
Just a few thoughts.
If it were me, I'd go head over heels for a nice dinner and the LotR DVD.
