You can easily upgrade from Fedora 16 to Fedora 17. And when I say easy, I mean two commands easy:
As root:
# yum install preupgrade
# preupgrade
The preupgrader will fetch the packages needed for the upgrade to Fedora 17. After reboot (choose Fedora 17 in the grub) the downloaded packages will be installed and Fedora 17 will be ready to use.