The rear hub was a 3 speed Shimano Nexus with a roller brake (which my wife is interested in). The owner was gracious and was also stuck at the playground so I had a chance to look at the bike closely - in between running after my younger boy on his various excursions.
It seems the owner has the same conundrum that we have - what kind of gearing works best for someone who lives at the top of the hill in one of the northwest 'burbs. I'd like the think that the Nexus 8 speed hub would work for us. Using Sheldon Brown's Gear Calculator, I figured out that the 8 speed hub had a lower gearing than my 30/39/50, 12/32 gearing on my Surly. The 30/32 combination gets me up the hill to our house fairly easily with either a boy in the bike seat or a boy in the Burley or both! So, perhaps, the 8 speed is the way to go.