When I was 12, I received one of my favorite Christmas presents ever - my very own Swiss Army Knife. I used that knife throughout my Boy Scout years and into my college days, before I finally lost it. I never did figure out what happened to it.
I still carry a Swiss Army Knife everyday. My current one is the Hiker model by Victorinox, which I've had since 2010. Its tools include two knife blades (small/large), two straight-edge screwdrivers (small/regular), Phillips screwdriver, can opener, bottle opener, wire stripper, wood saw, reamer (awl) with eyelet, tweezers, and toothpick. It also has a ring to attach it to a keychain or lanyard. It also has the "secret compartment" found on many Swiss army knives where you can store a sewing needle or pin.
Many people never realize the needle storage compartment exists, but it is an intentional design feature by Victorinox, specifically to hold a needle or pin. To find it, simply open up the Phillips screwdriver and look for the tiny hole in the red casing near the base of the screwdriver. A sewing needle or pin fits perfectly, though I find a pin works better because its head makes it easier to insert and get out. You have to supply the needle or pin.
A Swiss Army Knife is much more than just a pocket knife. It is a fully-functioning multi-tool. I've had the Victorinox Tinker models in the past, and now carry the Hiker (which is the Tinker plus a wood saw). I've used them many times for all sorts of repair jobs, from replacing door knobs to putting up bird houses, and they have proved quite rugged and durable. The screwdrivers on mine get used as much as the knife blades do, and have always done the job. The wood saw is the best on any multi-tool I've ever seen, and is VERY sharp, easily handling wood up to an inch thick.
The knife blades come quite sharp too, and are easy to maintain. I am not an expert knife-sharpener, putting my skills more in the "intermediate" range. However, Victorinox does sell a sharpener specifically designed for their knives, and I am able to keep an excellent edge on mine with it.
Speaking of the knife blades: I use my large blade for most day-to-day tasks, saving the smaller blade for more detailed work. Other folks use the smaller blade for daily tasks, and keep the larger blade clean to cut food. How you use them is up to you.
One advantage of a Swiss Army Knife is that most folks don't find it as threatening or intimidating as a regular knife. This is especially useful in an urban environment where folks may not be used to people carrying knives. A Swiss Army Knife may work well as part of a "gray-man disguise."
Of course, know the laws and regulations for knives in your area.