Here are just a few suggestions of places where the sling can be invaluable. If you have any others do share them and I'll add to the list:
Public transport
Does your station have stairs and no lift? What about the tube stop you want to go to? How hard is it to collapse a buggy in one hand with baby and bag in the other, hail the bus, pay and get on? Put baby in the sling, a small backpack on and you're off! Easy to get on and off the bus, tube & train without waiting for the kindness of strangers to lug the buggy & baby up steps for you.
Big family party or wedding
If baby is under 6 months old you could also turn the sling into a pouch again and use for a nap during a long day out, such as at a wedding. If you're wearing the right kind of top, the pouch can also be used for discreet breastfeeding. Can be very handy if baby starts getting upset during the ceremony / big speech!
Help you lose weight
Going for long walks with baby in the pram might seem like a good bit of exercise but how much more exercise to go for walks and carry baby too! Can also help you to cover terrain that a buggy might struggle with.
Going to your favourite restaurant
No space to park the buggy in between the tables? No harness on the restaurants high chair? No problem! Swan in with baby in fabulous sling, take baby out and pop in highchair and secure with sling round baby's waist, making a cushion with the tail for added panache!
Supermarket trolley
Loop the sling around baby's waist and fold tail to make cushion. Comfortable and secure
At the airport
Checked your bags into the hold? Checked your buggy into the hold? Great, only another 2 hours to mooch round duty free before walking 2 miles to your plane before take off!! Sling can easily fit in your hand luggage and may even count as clothing and helps you carry your baby around a busy, noisy and sometimes frightening airport. Sling can then be used as a blanket or burp cloth once on the plane.
Whilst on holiday
You may also start to see a subtle difference in the way you view your baby in that they are part of the experience of getting on the bus or train or going round a museum, rather than being just part of a cumbersome pushchair that's hard to manouvre and where your baby or toddler only sees the backs of people's legs!