As a Nasus player, I know that I used to recommend Vladimir as a good pick against Nasus due to his ranged harass (letting him chunk you under tower safely), good durability and sustain (letting him trade with you constantly), reasonable sustained damage, and ability to kite Nasus during duels and teamfights (due to his synergy with Rylai's Crystal Scepter).
I know that when I used to play Vladimir against durable enemies, I would generally rush Hextech Revolver (sustain), Rylai's Crystal Scepter (bulk and kiting) and Void Staff (to negate whatever MR they decided to purchase against me) and it would work out pretty well.
Though, I haven't actually played that match-up (from either side) since 6.9.
I should probably try Vladimir again at some point...