My favorite is a renovated Myshuno Meadows which I got from the gallery and then further modified myself. The downside, of course, is that an outdoor wedding doesn't work well in Winter and you have to schedule it for a day where it won't rain. Still, I do about 3 out of 4 weddings there.
Here's the most recent wedding I had there:
https://64.media.tumblr.com/438cdd5e705359ff8b944fe9bf0458b1/d71b10ab49ca606a-a6/s1280x1920/75924a56b900af37f742d38707644a8468d736f9.jpg
For the rest I usually bring in different indoor wedding venues off the gallery just for that one wedding and then I switch it back to whatever the lot normally is when the wedding is over. I do that so I can experience a bunch of different wedding locations. There's dozens of really lovely venues for weddings on the gallery and just not enough space to dedicate lots to all of them all of the time.