ESXi/vSphere/vCenter Upgrade 5.0-5.5

Our current environment is:

8 Nutanix hosts running ESXi 5.0

1 vCenter Server running 5.0 with SQL Express

Horizon View 5.1.1

I'd like to upgrade to ESXi 5.5 and vCenter 5.5.  I also want to build new servers for vCenter, SQL 2012 and VUM.

What would be the best way to go about this?  Should I build the new vCenter servers, do a migration to them, then do the ESXi upgrades?  Upgrading Horizon View isn't as important but would it be best to do that at the same time?

Thanks!