Demote a Windows 2003 Domain Controller

I have a Windows 2003 DC that was the only DC here at a small company. I recently add two virtual Windows 2012 R2 DC's to the domain on ESXi 5.5. I have one ESXi 5.5 located at the main office running a 2012 R2 DC and one at a remote office connected by a VPN. I want to demote the 2003 to a members server "there are some apps that are running currently that we still need. I will decommission the server at a later date". I know I can run dcpromo to demote the 2003 DC but what steps do I need to take to make sure everything is functioning correctly on the new DC's? I did some searches and read some write-ups but I also wanted to ask here.