Personally I would sit down with her and look through fish on a site like liveaquaria or petsolutions to get a better idea of what she likes. Many times I've had people simply wanting colorful fish get excited about "unusual" fish like apistos. An interesting pattern, body shape etc can go a long way to excite people. I find that most of the time when people ask for colorful fish, it's because all they can picture are the dull, common fish offered by petco.
Once you have an idea of other things she might be interested in, you can look around aquabid or other places for species you both can get excited about. I think everyone here already gave a great starting point for specific suggestions
Once you have an idea of other things she might be interested in, you can look around aquabid or other places for species you both can get excited about. I think everyone here already gave a great starting point for specific suggestions