Ed Wagner (7/31/2014)
Jason is braver than I am by upgrading in place. I've had SP installations fail, so I'm a bit wary of upgrading in-place.When I upgrade, I do so to a new server. I use the backup/restore method to migrate the databases, usually in groups of several databases at a time. I script every backup/restore command ahead of time and test before the actual production move. This also gives developers the opportunity to test their applications while the old databases are still in production.
When it comes time to do the actual production move, you already have everything scripted and tested so there won't be any surprises.
The time to actually perform the move is used by others to point their applications to the new server.
If disaster strikes during the move, the fallback position is to keep using the original databases until the next blackout window.
And of course, the really smart people (are they??) may also make use of DNS redirection so that applications don't have to change connection strings. Just use DNS to point to the new server with the old name. Hopefully the old name is actually generic for the application(s) and has no relation to any actual server name past, present, or future. Think about it, makes changing servers easier.