I just level 32 with my assassin/thief and don't know if I should do the dark brotherhood or the thieves guild. 1000 hours in and never did them. What outfit do you think would fit my character?

Thieves Guild armor is pretty good. Strange enchantments for an assassin though.

But for both, Nightingale Armor.

Only level 32 with 1,000 hours?

If you don't plan on doing the Brotherhood,http://www.uesp.net/wiki/Skyrim:Linwe%27s_Armor#Linwe.27s_Armor is a fine choice for any thief not afraid to lift a blade.

Haha nah, 1000 hours over several characters, usually up to 45-50. Thanks for the suggestions. Maybe I'll do dark brother hood first then thieves.

Unless you like dressing up as a gimp, don't join the Dark Brotherhood if it's outfits and armor that are your prime focus. You'll probably find a more fitting look by joining the Thieves' Guild. However, as for the guilds themselves, the Dark Brotherhood probably has the best quest line, IMO.

tavern clothes and boots.

Linwe's Armour or Thieves Guild Armour.

Nightingale is too batmanish. DB is awful.

Vanilla leather armour is also ok.

Slight faction armor spoiler:

The dark brotherhood armor leaves a lot to be desired.

Vampire armour with your own enchantments on it would fit the bill.

Nightingale looks fine. DB armor is hideous.