My only scrap of wisdom would be that I've heard a lot of readers say they hate epilogues (at least, those that are very firm about where characters "end up" too far into the future) because they want to be able to imagine the characters going for more adventures, and epilogues too often close too many doors. [And I think the Hunger Games ending is an example. I understand why it's there, because she was considering young readers, who wanted/needed to feel like poor Katnis got some happily ever after of SOME kind, but it didn't really work for me on several levels, and I don't even mind epilogues. I wonder how anyone else felt.]
So I would avoid making the ending TOO absolute/far-seeing/"and nothing interesting ever happened again." For my third, The Skeleton's Knife, I actually planted a hint for what a continuing adventure might likely be, even though I have absolutely no intention of writing it -- because it relates to the thematic point of that third book, which is that my MC is looking to the future and continuing adventures.
I do think it's important for the characters to get to a comfortable/clear emotional point at the end -- where the reader knows they'll be okay, no matter what. (Which was sorta Katniss's problem -- she really WASN'T going to be okay, it's a big stretch to believe the "mostly happy family with Peeta" thing, and personally I think Suzanne Collins should have let the series be the tragedy it really wanted to be. But that might have been a tough sell in the kidlit world.) I think tying up technical/plot loose ends are less important than that emotional resting point and the thematic conclusion that we reach as a result.