Yes Penny's is smaller or there are rooms we haven't seen... Sheldon and Leonard's place might have been two or many apartments originally converted into a single domicile at some point... or Vice versus that penny's apartment is half of what the architect considered. Lets not forget that they might still be paying off the elevator and post 911, they're also probably paying off the super not to have Homeland security on their ass.
That was Monica's nana's rent controlled apartment, and according to Monicas conversations with the landlord, Nana still lived there and they were paying the same rent Nana had been since 1942.
Of course when they swapped apartments it's inconceivable someone didn't raise a fuss, especially if Chandlars rent had been calculated in the 1990s?
King of Queens? Dudes in a Union. Might as well be in the mob. They get a pay raise every other month and if there's talk about downsizing or redundancy, someone is sleeping with the fishes.