Eirikur Eiriksson (5/7/2014)
If I remember correctly, you'll have an upgrade grace period, you could install a new instance on the/a box, run the two in parallel for that period while migrating the data from the old to the new. Better check with Microsoft first though.😎
In place upgrades from standard to enterprise work just fine, no need for the two side by side. But that obviously depends on the confidence in your self of being able to rectify it if the upgrade goes tits up.
Personally.. I would back up all of the databases, export all SSIS packages if there are any saved, script out all of the users etc. You could run a server backup just incase for added security, run the in place upgrade and test.