I usually just go to the the San Myshuno park or another lot with the wedding arch on it. I did used to use a 'church' lot I got from the gallery, but I figured it didn't really fit my sims much.
For me, weddings aren't too big of a deal in my game. I might take some screenshots, but a lot of the time my sims will just elope on the spot in a pretty location or just not bother getting married as it doesn't make much of a difference if they are or not. My sims would probably get married more if the step-parents and aunt & uncle in-laws were recognised in the relationship panel.
