If there isn't a specific reason, does it have to be a surprise?
Can you make it more of an "experience" (see what I did there?) and take her out watch shopping? If the gift is for her, make it a gift you know she'll like.
I'm guilty of buying things I like for other people that maybe wouldn't be their first choice. A watch is very personal, and I don't think buying it together would lessen the special-ness of the gift.
2 cents, everyone's got one type of thing!
Here's mine, a slick quartz solar model. I think the idea of a worldtimer is more appealing to me than in actuality though, as I've tried to use it for travel across timezones, and it's always difficult to reset the time and determine the offset. As a multiple caller-type I think it's great, but for travel I'd prefer a traveller-type gmt, preferably with a bezel for a third timezone (UTC, local, and home).
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