Would any modders be willing to create some method that allows us to return to the Sierra Madre Casino and Villa areas? A simple version would allow return to the area as we leave it after completing the story. It works fine as is. Setting the Ghost People in and around the villa to respawn would be a nice addition though too.
Colleen made a great mod that allowed returning to Anchorage for FO3 that I envision working in a similar way. Maybe a two way vertibird trip? Put one of those Enclave beacons next to the entrance to the abandoned BoS bunker that sends you to the main entry gate by the fountain in the villa, and then park a static vertibird that sends you back to the beacon when clicked?