My home is 450 feet above my office. Most of my routes home are 9 miles, one, which is less safe is 7 miles. On the way in to work the 9 mile routes take about 40 minutes, and the 7 mile route takes about 30 minutes. On the way home however, they take about the same time, about 48 minutes because I am slogging up longer inclines on the shorter route. The are a couple of short steep hills on my longer rides home, with more flat sections which I like. So my preference would be the shorter steeper climb on your route, however, I'd mix it up for variety.