we have DR servers at a remote location. most apps are java and use sql logins and we have a db/tables that we use to point apps to servers and db's. the app server has a local text file that tells it which alias db to go to. each alias db has a table with the info. just edit the file to point it to a new server

on the remote server we already have the sql logins set up. for windows authenication if you use groups instead of creating a separate login for everyone it's a lot easier to manage