Also consider the length of the rod. Most women are better off with a rod in the 7'6 range to 8'6" range when dealing with rods in weights less then a 6-wt rod.
Instead of trying to surprise her with a rod that may or may not work for her casting stroke, take her in and let her test some diffrent rods out to find one she likes the feel of. If you want to surprise her, you could have the already purchased reel in a box already since the reel will not effect the feel of casting in any large way like the rod and line will.
Also if you take her to a shop to test out rods to buy the staff will most likely help her with her casting stroke and as us men all know she will most likely be more willing to listen to advice of a stranger on casting more then she will listen to you her husband on the subject.