Third the sub panel, and oversize it. If people plan on using their garage a lot, I recommend they put in at least 100A sub panel. It's far better to pay the extra few bucks now than be running inside and resetting breakers when your compressor kicks in while the mash is just coming to a boil.
Also, don't say that you want a 60A gfci breaker, tell them you want a 60A spa panel beside the sub panel. It's far cheaper than paying for a gfci breaker. Or it is here in Canada anyway. If you have the sub panel, you don't even have to do anything right now for electric brewing.
One more thing, tell them you want a big sub panel. A lot of guys out in a dinky little panel and you run out of room right away. The difference between a 12/24 (24 circuits, 240v circuits take up 4 spaces) and a 32/64 is about $20. Again, same as supply size, cheap to do now, expensive later.
One last thing, make sure your wifi signal is good, if not, run some cat5e for an access point. And run some coax+cat5e for a future tv, you never know...