Since they will be visiting San Diego and San Francisco anyway ... I would choose one of the other cities!!
What does daughter like to do? Does she like hiking, does she want to see flora and fauna, does she like (need) shopping? Is there any climate that she dislikes??
Portland and Seattle can be quite *wet* in January/February - but if it were me I would still choose one of these cities. I like the Pacific Northwest - one of my favorite places to hike. Even if she's in the City - you don't have to travel far to be in the wide open spaces. Seattle has all of the waterways to explore, and Vancouver Island a short trip across the border and well worth the trip (she can add Canada to her list of countries - if this is possible on her VISA). Portland has *The Hood* and several other isolated volcano's that are sooo beautiful - and Columbia River Gorge is AWESOME scenery/hiking/fishing!!! Portland is a smaller city than Seattle.
Phoenix doesn't interest me at all, too hot and dry and too populated (with population pretty wide spread - you have to go further from the center to get to "breathing space"). But it does offer some great hiking adventures in the surrounding desert.
I've not been to Valdosta, the closest I've been is Macon - but I'm not a fan of the South East ... just not.
My choice would be Portland ... but a lot depends on what kind sights/sounds/surroundings your daughter wants to experience.