Where CAN you rest?

[FizzMan]

Compared to BG1 I've yet to find a single area in the game where I can rest...

[Yunocchi]

Early in the game, you have only three possible resting spots if I remember correct and two are locked behind quests. One is the secret exit from the morgue made by the anarchists. The first quest is the house just south of the morgue, if you talk to the wife she will give you a quest, if you accomplish it, she will allow you to rest at her house. The second quest is west of the morgue, the big house, you can't miss it. Inside you'll need to find the fork of some crazy guy for the owner, and he will allow you to sleep there for free.
Edit : Looks like I missed some, sorry for the mistake.

If you're in the buried village, Martha will allow you to rest for free.
If you're in the lower ward, Giltspur will offer inn services.
If you're in the clerk ward, the civic festhall, I think, offers such service too.

[rompier02]

Mebbeth in Ragpickers square. The dude who buys cranium rat tails will let you sleep when you ask him about his history in the Market area. This is relating to Sigil. Other planes requires conditions.

[philos3]

There is also an "inn", so to speak, in the center of the northwestern section of the hive. The innkeeper only charges a copper or two IIRC.

[Jerome Powell]

South-East house after you fix the contract with the man and the dusties you'll get a free place to rest all the time right at the start of the game