Footkerchief, as someone with extensive experience in this area I can tell you that you're just wrong. To most women, a day at a massage boutique has nothing to do with sexuality. It's a day of relaxation and pampering. You're just dead wrong.
There's a distinct difference between the associations men have with it and those women have, so it's an easy mistake to make. Most women who go there would get a mask, an extensive peticure, and perhaps a mudbath and/or backrub. It has absolutely nothing to do with sexual sensuality.
You just have to understand the difference in the way women see it and the way men do in order to get it. Once someone's explained that, it makes sense.
Edit: Sending her anything on Valentine's Day sends a message of its own. You could buy her a bag of catfood, and tell her it's for Valentine's Day, and a message of some kind would be sent. Your problem is sending a "friend" with whom you have no romantic associations a gift on a day for couples. You'd have to be very clever, charming, and/or quirky with a good previous relationship to pull that move off without looking like a dick. Believe me, I know: I pulled it off with flowers. It would be different if this were your best friend and you were doing it as a non-romantic nice gesture, but it's not. It sounds more like a girl who doesn't really want a more-than-friends relationship with you and has been giving you your space for a while.
But as I said in the first reply to this: Why are you asking us? You know her, we don't even know you. It's really only up to you.