December and January can get expensive because its high tourist season. I was intially considering January for my wedding but we thought it was going to be a little too expensive for our guests.
I agree with MarieSam - I wouldn't take June out of consideration. I got married in mid-June and the weather was hot but manageable because there was always a breeze. It did rain a couple times during my 10 day stay but the rain lasted for 15 minutes and was gone.