The Chevy Suburban might be a gigantic overwrought monster of a vehicle that most people have absolutely no business driving as a primary vehicle, but they do have their uses. Before I go any further I would like to point out that yes I do own a Suburban, but I got it for free, and it just sits there most of the time while I drive my Geo Metro.
First I would like to clear up a misconception related to gas mileage. The Suburban is not unique in the fact that it doesn't get very good gas mileage. They are body-on-frame trucks and they all get terrible gas mileage, even the 4 cylinder ones. Two wheel drive Suburbans actually get around 18 miles to the gallon on the highway, which certainly isn't great, but it beats almost every 4-wheel drive vehicle on the market, and it is shockingly close to what the Chevrolet S-10, Ford Ranger and other compact trucks get. Depending on the options the Suburban might very well get better gas mileage. The Suburban I own seems to get about 17 miles to the gallon, it is a 1989 model, with the 5.7 liter V8 engine. It would probably get 18, but it has a sort of conversion van type topper on it, that raises the roof about a foot. Prior to owning the Suburban I owned a Ford Ranger with the standard cab, 2.8 liter V6 engine and a long bed. The Ford Ranger got 19 miles to the gallon. The difference is so small that it is barely even a factor. Figuring fuel cost at $3 a gallon it is only a $100 difference per year for a 12,000 mile per year driver. A long time ago I owned a 4 cylinder Dodge D50 with an automatic transmission and it got an absolutely mind boggling 15 miles to the gallon, it wasn't even an extended cab or a 4 wheel drive or anything, it just got terrible mileage naturally.
The Suburban is most useful for very large families who would prefer not to drive a van (which I wouldn't blame them for, most vans get gas mileage just as poor, and very few of them can match the utility or reliablity of the Suburban). Other people who might actually need such a monster of a vehicle as a daily driver include people who need a tow vehicle, and people who need a large truck or van for business reasons.
Unfortunately 90 percent of the people who drive these beasts on a daily basis have absolutely no reason to own a monster vehicle.
Where the Suburban absolutely shines though is as a second vehicle. They can do anything, go anywhere, haul anything, tow anything, carry anyone, and are not very likely to have a breakdown. The ones up until they stopped putting the 5.7 V8 in them are one of the most time tested and reliable vehicles ever made. They are a continual tweaking of a design that came out in the 1960s and it was reliable even then. They even made the exact same body style for 20 model years in a row (from the early 70s through the early 90s). When I need a part for my Suburban (which isn't often, nothing has ever actually failed on it, although I have replaced things like fenders and interior pieces) I can go to the junkyard and pull a part from almost any Chevy truck made in the last 30 years. Both my front fenders are from a 1977 model, my rear bumper is from a 1983.
So to sum up, a Suburban with a soccer ball sticker on it being driven by a woman talking on her cell phone is a bad thing, but one sitting there that gets called into service every once in a while is great. Recent years have actually been a great time to pick up an old Suburban, the market is so flooded with giant SUVs that the older ones can be had for a song.