just thought of something else..
what about getting an appointment for her to have a facial or her nails done or a massage at a local beauty parlour type thing.. or if you could book her into a health spa type thing with one of her friends so she could have someone to go with unless you booked yourself in too!
and
jostar's idea's are really good too, the new ipod's are brilliant esp. the coloured ones i have one in bright pink - which would be good if she is girly.
http://www.apple.com/uk/ipod/imaging/ - thats a link to the ipod store where you choose the ipod then you can get it engraved for free.
i also think that a romantic weekend away would be great, if money isn't an object you could always get a cheap flight from jet2.com and go to paris for the weekend!!
hope this helps xx :-)