I think that the Gospel according to Mark has a wonderfully appropriate ending. The last verse of the text for Easter Sunday—and of the entire account—goes this way (in the ESV): ‘And they [the women] went out and fled from the tomb, for trembling and astonishment had seized them, and they said nothing to anyone, for they were afraid.’
If you take the Gospel according to Mark as a whole, it is certainly an appropriate ending. The beginning of this account was just as abrupt.
Jesus had already grown up; there are just a few verses about John the Baptist and his immense popularity. When Jesus shows up, the heavens are ripped open, and he is called God’s Son. I think that even more important is the fact that Jesus starts to tell people to repent and believe in the gospel.
This is an extremely early quotation of what Jesus said. It is important to note that the word ‘gospel’ is extremely important to him.
The first verse of the entire account states that this is the BEGINNING of the gospel of Jesus Christ. It is certainly not the end.
When this gospel account is in its normal spot as the second of the four accounts, this short ending is certainly appropriate. In some manuscripts, though, this gospel account is the last of the four.
With this account as the last of the four, the two apostles who wrote are first (Matthew and John), and then the two secretaries who wrote are second (Luke and Mark). Also, the longer account is put first, and that is the normal ordering as well for that time period.
Having the four accounts ordered in such a way makes some sense. It focuses your attention more on the reliability of the work as a whole. And it also makes some sense to have, at the end of such a massive work, a better ending than the women leaving the tomb and not saying anything to anyone.
The ending that appears in some manuscripts, 16:9-20, has components from the other gospel accounts, and that is okay as well. I would encourage you not to think of these four accounts as written by four people in four different areas throughout the Roman Empire to be read in front of four different churches.
The four different accounts are meant to be four different perspectives of an extremely gracious God. And THAT is a good point to end on for ANY Sunday of the year.