For wedding and parties, it all depends on what's your style. Some photographers like to isolate detail, so they use 50mm f/1.4. If you're going to do a lot of static portraits, 85mm f/1.4. Static, because many of the 85mm lenses focus quite slowly due to the massive amount of glass the motor has to move (from my experience with both the Canon 85mm 1.2 and Sony CZ 85mm 1.4). Then there are others who like to stand far and shoot close - 70-200 f/2.8, or shoot to capture sweeping scenes of the venue with an 8mm fisheye.
Also, how do you want to shoot your event? For weddings where you want to capture "mood", ambient light would be nice, so fast aperture lenses would be needed. For party shots, guests might want to see their faces clearly, so flash would be used, thus normal lenses would do.
You really have to think of your requirements and style and when you do, it'll be easier to find the perfect lens for you.