I personally would like to see more added to Fallout: New Vegas. It felt a little too small. By this I mean, the map seemed smaller and only four DLC this time (of course I'm comparing to it's predecessor: Fallout 3) made me a bit sad. Now, I don't want to seem like one of those people who compares everything to another game. After all, New Vegas and Fallout 3 are different in many ways and are amazing games in their own way. But it was just something I noticed and one of the reasons I loved Fallout 3 so much was because of all the content to it. Granted New Vegas did add a lot to the game (weapons, weapon attachments, aiming down the sight, more consumables, crafting, ect.). And although all these great things have been added, I felt that there was more that could have been added.
Perhaps the one thing I would like to see most is one more add-on after Lonesome Road. I don't know much about Lonesome Road considering that it hasn't been released yet, but I'm sure it's going to be a fantastic DLC like all the other DLCs for New Vegas. But one idea that really stuck out in my mind is a possible Area 51 DLC. I loved Mothership Zeta in Fallout 3 and I thought it would be cool to bring aliens back into New Vegas (other than the Alien Blaster, of course). There is a lot you could do with an Area 51 expansion. Addition of aliens, mutants. The possible weapons would be amazing. Maybe add a sense of horror to it.
These were just my opinions and I don't expect any of what I stated to happen. Just getting an idea out there. Tell me what you guys think about all this.