The Mertz's Apartment Building
Fred and Ethel(landlords of Lucy and Ricky),had what is called in NYC a "walk up tenament" building. Basically a type of row house with anywhere from four to five stories, maybe six. Such buildings usually were built as priviate homes and converted/divided up later into apartments.
Another type of tenament were large apartment buildings which featured many apartments and may have had elevators.
IIRC the building (according to the address given during the show) was on East 68th Street in the 400's. That would have put it near Second to First Avenues, which at that time (1950's) was mostly working class tenament apartments and "brownstone" type apartments. Note the El (elevated subway trains) are often referred to and they ran up Third and I *think* Second Avenue.
Seeing the "outside" of a TV programme's building does not always help since the layout used for interior shots many times does not make sense based on how the outside looks.
For instance in Lucy's apartment there is the large kitchen with a back door and terrace. Some episodes their was a large window always in view during the living room shot (over the piano),from which sometimes Lucy would look out of to see what was happening on the street. In one episode the milkman runs through the Ricardo's bedroom to use the back fire escape to get away from a jealous husband. This would mean either the Ricardo's bedroom faced the back (but the alley off the kitchen faces the back), or faces the street (but the window off the living room faces the street). Seems impossible to have a "real" NYC apartment given true building lots.
Even in "Bewitched" the interior shots/layout of some rooms does not make sense with how the home was pictured from the outside.
Regarding the Honeymooners:
Compared to Trixe and Norton, Alice and Ralph lived in the stone age! Trixe had many of the mod cons of the day, Alice still had an icebox, bare walls and bare sink. Alice's home was what is then known as a "cold water flat". Meaning just that, their usually wasn't hot water supplied with the apartment, and in some cases no bathtub/shower. One either had a small bathtub/sink in the kitchen or hauled a large tub into the kitchen and boiled water for a bath.
IIRC the excuse given for the difference between the living standards of the Norton's and Cramden's was Ed was willing to buy things on credit, Ralph was too cheap/would not.
Launderess