Do you happen to know the wattage of current fixture? You can use as jumping off point whether you need more or less - compare to the "new" way of measuring light, lumens vs. wattage. Do you want LEDs? Are you rewiring as older romex in the walls might not be able to handle stuff like halogen. We are putting in recessed light in the bath ceiling (2 in main area) and three sconces next to mirrors above vanity. I have heard it is better to have side lighting by your mirrors for tasks like shaving, or makeup application, instead of lights above mirror. You might also want to see if anyone has posted recommendations in the lighting forum.