I truly dislike giving Hallmark cards. Their slogan is something like 'when you care enough to send the very best' -- instead I always feel it is more like 'when you care so little you pop into the most convenient store in the mall' and pick out a card. It is essential to me that when the recipient gets a card I have sent, that they know, 1) exactly who it was from from the card itself (as opposed to my name being on it), and that I obviously picked it out for them, specifically, again, just from the card itself. Most of my card sources are small, boutique florists/gift stores that carry cards from smaller labels, not Hallmark, American Greetings, Gibson, et al. For more 'available' places: Barnes & Noble occasionally has some 'different' cards, as do
some of the larger, better grocery stores here in the Northeast US. I have also bought vintage greeting cards. I had a store near me that used to carry cards from here, a lovely little English stationer (I find I appreciate the English aesthetic in things, as well as the non-standard sizing). It is interesting to tell someone, after they have commented on the card, that you had it imported from England.
http://www.judyballcards.co.uk/ If I knew someone in the SO or potential SO class, I would certainly buy some handmade paper and commission a student artist (college art students like commissions) to do something very specifically tailored to the Lady and the occasion, then get a calligrapher to write the inscription. This may be an option for you. Also, if you are of a literary bent, compose a love lettert, and handwrite it with care on good stationary. I don't have and SO, but the ladies to whom I have sent handwritten personal letters (not always in an amorous sense, even just a thank-you) have always said they would keep them forever. IOW, invested effort, thought and emotion does seem to pay off. Good luck and congrats, Huntsman