Originally Posted by
DrIsotope
My recommendation for a first-timer is a loop route-- starting and ending at your house-- of ~34 miles. For your first imperial century, I recommend keeping the elevation gain to a relative minimum-- say ~4,000ft of total gain, around 1,200-1,400ft per loop at the most. Ride it three times. If you decide "today is not the day," and bail after two loops, you've still ridden a metric. The first two loops will be easy. The last twenty miles (at least for me) is when I start asking myself unanswerable questions. Even now, after having done my fair share of them.
I did a cloverleaf century a few weeks ago and it was really nice, I've done dozens of regular loop centuries but never thought to just come back home so I could eat lunch there instead, it's definitely a great way to go for a first century.