The Vault is simply a gold mine of xp and items. But first it is imperative to talk to McLure instead of Lynette because she will get you banished if she knows you haven't erradicated every ghoul on sight.
The first level, the medical bay is ripe for the xp taking. Phyllis can be taught about freeing herself with a speech check and you can pursue things further with her is you have the kama sutra perk or ladykiller. With PE 6 or above she can be explained that there are no children in vault city and that they should start worrying. If you're chatacter is male they can donate to the "sperm bank".
The doctor here gives us a 5% increase in our medical skills if they are 75 or above and the Vault city inoculations perk , that gives us more resistance to poison and radiation.
He asks for a sample of jet to help develop a cure. We give him one now but we will be able to find a cure of our own in the near future (and abuse a trick involving Jet and the antidote).
The computer benhid Phily's main function is to provide with the info on combat implants, again if your doctor skill is 75% or above. Althrough the doctor in the Vault will refuse to performing the operations there are other people more willing.
The second floor has tons of goodies to loot but for the sake of reminder, only the voice module will be useful to us for plot related reasons. The rest is just payment.
Next time : the third floor.

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