A sofa set makes sense if you have an actual living room to put one in, enough space for a sofa and two chairs, or a sofa and a loveseat, to sit in real conversation with each other rather than lined up against a wall like they're waiting for a bus. If your living room is also your dining room and your home office and sometimes your guest room, think twice. A matching set wants room to breathe and commits you to a look across three or four pieces at once, which is a lot to walk back if you change your mind in two years.
The colors that make a set easy to live with over time are the ones that don't ask for anything: oatmeal, a warm gray, a soft clay or putty tone, anything that sits quietly under morning light and doesn't fight the room when the sun drops low in the evening and everything goes a bit amber. I made the mistake once of buying a set in a bright cognac leather because it looked rich in the store, and it read as "dad's law office" the second it landed in my actual living room, under actual ceiling light, at eight at night. Where a set genuinely falls short is in smaller or oddly shaped rooms, rentals where you might move in eighteen months, or households with a lot of foot traffic through the middle of the room, since matching pieces lock you into one arrangement and don't like being split up or pushed into corners.
A good set ages the way most upholstered furniture does, which is to say the cushions soften and need plumping, the fabric on the arms wears first because that's where everyone actually touches it, and pets or kids will find whatever is most expensive to clean and head straight for it. Rotate the cushions every few weeks so one spot doesn't take all the sitting, vacuum the crevices before crumbs turn into a permanent feature, and if you can, get the fabric treated or buy one with a removable, washable cover, because spot cleaning a fixed cover for four years straight is its own kind of chore. Nothing ruins the look of a set faster than cushions that have gone flat on one end and full on the other, like the sofa is tired of holding up its half of the deal.
The detail that makes a set a pleasure rather than just furniture is when the chair and sofa cushions are interchangeable, so you can swap a worn one in without anyone noticing which seat used to be the good one.