Texas: Was it's own COUNTRY for a while
The only state enter the us under treaty
Has Chuck Norris
Has an economy large enough to support itself and once again succeeded(sp?)
Largest state in the Continental US
Plus, Texas totally rocks the Casaba.
Can't forget that texas is one of the states that has an express lane for executions and lets you shoot trespassers on your property no questions asked if it's after 6:00 pm.

Dealing with the OPs original thoughts I wouldn't mind something dealing with the common wealth, but if they add some back story to it. Maybe have a quest where their robots just went renegade and they had to move to a new location in New Vegas. We can't forget now that this game has a chronological order in-game lore wise where it takes place 3 years *I think it's 3* after FO3. With three years that's more than enough time to move your butt to a new area and setup shop there. Probably take them a month to get to New Vegas, but even then that leaves them 11 months and 2 years to setup shop ready for our new wandering character.
My only question would be taking zimmer along or should they say they haven't heard back from him. Know that we have the option to off his sorry hide or we can turn in A3-21 so it's hard to say how to continue it. For me personally I would opt for the "missing" part with a bit of sarcasm because he could be killed by one of the renegade robots he created or by us which would work both ways.