I usually include a little night too... sometimes a lot of night.

That is one-way headed to Portland one day, back another day. I've ridden up to Salem and back RT a couple of times which also makes for a long ride.

Only once, or twice, was I able to finish the ride mostly in daylight.

I vary my route course considerably, from a low of about 130 to 140 miles, and a high of about 186 miles. I can hit 200 by adding a little extra on the ends of the ride.

We have the "Willamette Valley Scenic Bikeway", mostly on not too busy rural roads, but the course design is to go a little here, and a little there, and little up, and a little down. To pass by as many cities and towns between Eugene and Portland as possible. While the actual Scenic Bikeway route is only about 140 miles, it adds another 40 or 50 miles or so at the two ends of the rides, and the total ride gets pretty long.

Keep in mind that the Willamette Valley is mostly flat. That is why it is called the Willamette Valley, slowly losing elevation heading northward, and gaining elevation southbound.

My first actual double century was Spring of 2017. I was going up for some hill climb rides in Portland.

RondePDX

Those are WICKED HILLS!!!

I was delayed until Friday due to the rain, and I rolled into Portland so late that I took a nap, and only did about 1/3 of the Saturday ride, then 100% of the Sunday ride (not real fast).