We both do! We have used a baby sling for all our children. We used it some with the first, more with the second, and by the fourth were convinced that baby slings are necessary baby gear. Slings are great for fussy babies, and carrying babies in places that are too crowded for strollers or backpacks. We've used ours a lot as a secondary carrier when you want to put one child in the backpack carrier, but still need to carry another child. They are also great for nursing when you are out and about, but then of course, it would only be the mom who wears the sling in the family.
We have had several types of slings over the years. This great sling, that our 18 month old is in, is made by Slinglings. It is a pouch style sling with a small bit of padding on the inner rail for the baby's legs. The pouch slings are great because they are very compact, portable, and comfortable.
There is a learning curve when using a sling. It can take a few tries to feel comfortable with the carrying positions. Slinglings includes the best instruction book I've seen yet. It is colorful and gives step by step instructions, with pictures, on how to position your baby in the sling.
Slings can be used from birth until the baby is about 35 pounds. If you have never used a sling before, and have a child this age, you should try it. We would be lost without ours.