I've always thought that doing something with the Searchlight airport - say giving it to the Legion to mirror the NCR's own McCarren, as a secret solidified staging point with its own prisoners could be a valuable balance and explain even more of how the Legion patrols are getting past the NCR (they start there instead of weird and obvious staging point right near some dangerous radioactive mutants, I mean "feral ghouls") - leaving the Legion camp for the big scary, distracting monster on the horizon. Have it offer counter missions (or just offer these instead of the NCR ones) - discourage beef and spice supplies by leaning on merchants with threats of legion violence, or set up Jacobstown to appear (or actually be) Legion aligned to distract the NCR on more fronts. Have Vulpes be there, not the camp, and be the sneaky mastermind behind sending patrols.
Honestly more for House to do wouldn't be bad either. Having more to do with his tunnels (or even the massive aquifers under the casinos needing protected) below the city maybe, could all have been valuable. Maybe even a planned evacuation monorail beneath the city that went to somewhere remote like Searchlight and his needing you to secure it before the legion hijacks it for something.
Really just more to do with the deep south of the Map, where there's a lot of room and some interesting bits but even less reason to explore down there. Even out east has the deathclaws for a one shot trip at high level. Although more there, maybe even attempts for legion taming of Deathclaws, could have been shocking and the chance to get mind sets from the Enclave remnants to use could have been more valuable, and differentiating, for the ending Dam fight. NCR gets drive-by & drop off Enclave power suits backing it, for irony and a perhaps a little dark symbolism, while the Legion gets a few more controlled feral creatures held by the most fragile of technological tethers and representing in a small way the synthesis (or corruption) of Caesar's ideals. Yes man, I'd say, gets some sort of additional technological upgrade that allows him to scramble enemy comms and raises the question if he'll start controlling information without you, or if the Enclave remnants - for all their old and tired talk - will manipulate him over after you leave. House is offered the Enclave officer aid and Comms but turns them down out of distrust for shadow government interventionism, instead accepting their remaining power armor for research and automation. Making it similar to the NCR but without the Enclave officers actually being put to use. The last two are pretty iffy actually but that's how I'd lower the NCR ubiquity - just give more for the Legion to do from a more relevant (read: closer) secure place that the NCR isn't comfortable touching. Heck give the player the chance to report it and the NCR just write it off as being too distant to be assaulted and held, too near a irradiated town to be healthy, and too flat to approach without completely letting the enemy know they're coming.
