Tips for Surviving the Sierra Madre
Light Step Perk will do wonders in the Sierra Madre because sometimes you just don't have time disarm a trap with a hoard of Ghost people swarming you and the red cloud just complicates things as far visibility issues when rushing through hazardous area. With a above average Unarmed or Melee skill allotment, scarce ammunition shouldn't be an issue because ammunition is scarce and weapon types aren't as plentiful since it's more about survival than thriving.
A key to counteracting the health draining cloud effects and the red cloud is by having available health boosting affects found from the Monocyte Breeder implant and the Solar Powered perk. With both you will have a reliving +2 health additionally if you have Dean in you party he will provide and extra 25% reduction which could dramatically diminish the effects. When indoors the +2 will regenerate you, making up for the lack of healing items.
Don't forget the Ghost people have the ability to just fall unconscious when they could have been killed so applying more damage to a limb will destroy them.
Science helps in using computers to outdo the Holograms. With high enough Sneak skill the holograms will be non the wiser even if they endanger you, as long as your out of sight and hide they will become passive again.
If your gaming style has been treasure hunting-like then you've obviously hit the mother load of caps-providing treats not found anywhere else in this amount! So if you have Pack Rat, Heavyweight (For those items you just can't let go!), Strong Back, Long Haul and Burden to Bear you're in for some serious dough! Whether you have one of these or more you raised you chance of carrying treasures a tad bit more or considerably. With Long Haul you definitely evened the score because you can now travel wherever you want to sell the treasures through Fast Traveling (after the quest is completed that is and you didn't end the game with a game ending option provided at the end).
--S P O I L E R------------------------------------------------------------ A trick to actually getting away with all the dough and beating Father Elijah would be to get all the dough, hide (Stealthboy is the key) get out the vault to your left and go around the area while he's getting into the vault and make it to the front door before the alarm goes off.
An invaluable treasure found nowhere else: Open purchase Weapon Repair kits. The Vending Machines actually sell these unlimited. I reached near the end of the add-on inadvertently with lots of Sierra Madre coins and found that Weapon Repair Kits were very much available for me to purchase. Keep in mind this item is rare (well it was for me) in the game and that they are actually quite accessible here and once you finish the last quest you will not get this offer again. Weapon Repair Kits can repair any equipped weapon of any price without spending a cap. Remember that one weapon that cost around 12k+ in caps to repair? I was able to repair those weapons from the kits i bought in Sierra Madre quite satisfyingly.