Moving Primary site to a data center

I'm looking for the most recommended solution here.

Here's the task. We are moving our current HQ site to a datacenter and the current site will then become more like a branch office. I trying to figure out the best method here. Should I

#1 create a new "Data Center" site and move the HQ DC's and subnets to that site on the day of move while leaving the "Branch" DC's and subnets in the current existing site.

OR

#2 Should I rename the existing "Branch" site to the "Data Center" site name, create a new "Branch" site and move all the needed "Branch" site info out of the renamed "Data Center" site to the "Branch" site.

Constraint of one weekend.

Suggestions?

Any other options? 

Thanks

RS