WonderCon Anaheim 2015 will be held April 3-5 at the Anaheim Convention Center. This again is Easter Weekend.
I haven't heard anything about WonderCon returning to San Francisco, other than that if it does, it would be in addition to Anaheim, most likely in the last three months of the year. I believe WonderCon Anaheim is here to stay.
Comic-Con International 2015 will be held July 9-12 (with Preview Night on July 8) at the San Diego Convention Center. If you have a 2014 badge, it may help you register for it so don't throw it away. I don't know why it's so early in the month this time.