Whenever any new person comes to home, my cat would keep sniffing the person and more so his/her clothes for several hours. Similarly if any new furniture or bag is brought my cat would keep sniffing for several hours. Why is it that my cat keeps sniffing anything new?
Smell is a much more significant sense for cats then it is for humans, they have in far more smell receptors in their noses than we do and there is the vomeronasal in the upper mouth as well. So their olfactory view of the world is much more detailed and complete then ours is, and they use it for communicating, for recognition, for hunting, for defense, for bonding the list goes on!
So if something changes in their environment or something new is added getting a comprehensive overview of it's scent is one of the first things they do and it's totally normal. As for the length of time they sniff for well depending on how complex or interesting the scent is that process can take a while. I'm not sure how accurately you've tracked it to get your "several hours" figure but I've seen mine give something interesting a good sniff on-and-off for in excess of an hour certainly.
Several hours of sniffing is more than just the time a cat needs to analyze the smell of a new furniture. But it is possible that the cat reacts to the smell of it. Every cat has smells they really like and they hate. And this can vary from cat to cat. Some cats really like the smell of solvents or glue (and some hate that). So it is possible that your cat loves the smell of new furnitures.