Usually when I do over 100 km I just go from my house and that is where I end.
But there have been a few times actually where I cycled from, or towards a destination. And while it is a little bit more work and organization, it really feels nicer. Like you are not just riding/training, but also on a trip. It is also possible to reach areas that would otherwise be too far away.
Off-topic
I once made a post on this forum asking whether anyone ever takes a train somewhere. In the past, when I was younger. I would look at the wind direction and then take a train as far as I thought I could still make it back in one piece with wind in my back. As a young person without access to a car etc. this was awesome. However, some people on the forum attacked me for it, going as far as to say my mom failed in my upbringing (because I would pick a direction based on wind direction). I just think I was a kid who liked to explore and see things. This is the part of riding to a destination that still appeals to me. When you do a loop, after a while you have ridden all the roads in your area.