I would definitely head north for a day... the town of Sayulita is amazing and has some of the best locations for weddings. Its a surfers town and its about 45 minutes away from Puerto Vallarta. There is a great hotel there called Villa Amor that I would check out... If you go farther north, there is a stretch of beautiful private homes along the beach that can be rented for weddings etc. I wrote on another thread about Casa China Blanca... its an incredible place.