This is a good question about the setting of place. Although not the only elements of setting in Barnaby Rudge, the Golden Key and the Varden Household are certainly significant. Let's take each of them in turn and attempt a description.
The Golden Key is simply the name for Gabriel Varden's home as well as the locksmith workshop. It is located in a suburb of London called Clerkenwell. Just like the Varden House, this is also a place that contradicts itself. Sometimes it is the home of honest laborers doing honest work for honest pay. Sometimes it is a place of argument between husband and wife. Sometimes it is a place of disagreement in the workplace when we are speaking about either the apprentice or the maid. There is also an interesting contradiction in the name "The Golden Key" because Gabriel Varden makes locks for the worst of places (such as prisons).
The Varden Household is more a question about character than about setting, although the kind of characters in the Varden Household certainly affects the overall feeling of the place. This is, generally, a good-hearted family and, as such, they have a good-hearted household. The head of the household, Gabriel Varden, is both good-natured and honest. He is unjustly abducted by the people rioting as they demand entrance to Newgate. Being the good man that he is, Gabriel resists the mob. Gabriel's daughter, Dolly, is also good-natured and talkative while Gabriel's wife is spoken of a bit less in the novel, but tends to be quite moody.
[Mrs. Varden is] a lady of what is commonly called an uncertain temper--a phrase which being interpreted signifies a temper tolerably certain to make everybody more or less uncomfortable.
Perhaps Mrs. Varden is Gabriel's vice, but it doesn't take away from the homey feeling at the hearth. All-in-all the Varden Household holds a normal family of the time, perhaps even one that is better than most.
In conclusion, although the Varden House is more about character while the Golden Key is more about setting, they both serve to add to Charles' Dickens' style in Barnaby Rudge.