I have found when in doubt give something that can be consumed. Find out their favorite food/drink etc. and just go one step beyond. If they are a tea drinker give a cool tea blend plus a new mug. If they are a beer drinker, give a selection of beers they probably haven't tried + a snack food that pairs well with them. It's not a new iPhone but it shows you know them and it's something you know they will definitely use.