Having recently catered my brother-out-law's wedding, there were a few things that I didn't think about, which seem more obvious in hindsight.
You're going to need to plan the beers so they have enough conditioning time. Going through the hottest part of the year shortly, you'll probably want to keep them cool too, so make sure you have enough cold storage space. All this time and kegs taken up means that you'll have a lot less for personal consumption over that period! Not only that, but it takes a while to restock (I'm only just getting back to a level I'm happy with and the wedding was 10 weeks ago
). It's good that you're thinking about it now, but bear in mind what season we're about to enter.
If you don't have someone "manning" the kegerator(s), prepare yourself for a lot of wasted beer. This was the most frustrating part for me; knowing how much time and effort went into making the beer and then seeing people towards the end of the night walking away from the kegerator with the tap still running. It really dampened my mood :angry: . I reckon I would have lost about 10L out of 6 taps over the course of the night (judging by drip tray emptying), and at least for the first half of the night, one of the caterers did most of the pouring. Some people just can't see past homebrew being "cheap" and are blinded to the waste. You might also get the bartender wanna-be's who think it's cool to always let the tap pour for a few seconds before putting a glass under it. Make sure you have someone to at least keep an eye on the drip trays and clean up any mess before it gets out of hand.
For what it's worth, I made 6 beers
50L Fat Yak knock-off (outsourced)
19L honey/lemon/ginger spiced wheat ale
19L Green Bullet hopped pale ale
19L Eurolager (think Becks)
19L Scottish Export (something more malt focused)
19L Chocolate porter
plus ~13L bottled ginger beer
There were about 80-90 guests with around half being beer drinkers. The beers are listed in order of how much was drunk out of the kegs, and we went through about 110L all up. I was pretty nervous at the start, but the beers ended up being very well received. Having said that, I'm not in a hurry to do anything like that again in the near future!
Cheers,
tallie