I don't own many lenses, simply because I just love the ones I do have. I always rent the 70-200mm for weddings, but only end up using it during the ceremony and, very rarely, during cocktail hour to get some shots of the guests without being a total creeper and in their face.
Truth be told, even at weddings, the 50mm hardly ever leaves my camera. It's the lens I recommend every camera owner buy asap. It's the lens I "forced" Suzy to get when she started helping me out at weddings. Since switching to a full frame camera late last year, my obsession with this little power guy has just gotten out of control. I absolutely love prime lenses and this dude just stole my heart. Portraits with this lens just turn out unbelievably amazing in my book. I've used others in its' place and was just always disappointed, so why even bother? Not pictured, by the way, is a second 50mm that I used to take this photo - Luke uses that one when he helps me out at weddings, and, should my prime man.. aehm.. I mean lens... ever break, I immediately have a backup. Yes, it's clearly an obsession.
I actually just added the 100mm this month and use it for all my detail shots in addition to, you guessed it, the 50mm.
The 16-35mm is the lens I purchase when I was still using a crop sensor camera since I needed something extra wide for those crammed bridal suites and dance floor actions. Now, it's just a tad too wide for portraits but I still use it if I can't use the 50mm and always, always to get some super awesome dance floor photos.
Will I add any lenses in the future? Yes, probably. For starters, I really want to get my hands on the 70-200mm so I can stop renting it - although I get a really good deal through my local camera store. I recently rented the Tamron version and really liked it so that might be another option.