I feel like I'm missing something. I've mostly been playing like Fallout 3 or FNV - running around doing quests and scavenging for loot.
I'm at level 15 now and I haven't done much with settlements. I have some people living in Sanctuary Hills and I've done a few of the Minuteman quests where you clear out an area for settlers. That's about it.
It seems like I need to be doing more, since settlements are apparently a big deal in Fallout 4. I'm not sure what advantage I get from having settlements other than a place to sleep.