I love my Ergo Carrier so very very much. We used it for G for over 2 years, and we use it for M now. We have quite a few carriers (slings, wraps, a mei tai), but Ergo is the one I'd recommend if you were only getting one.
I've had a few times when I've been out with it to eat at a place that didn't have a high chair (or all of them were taken) like, for example, the Costco food court I went to today.
So I figured out a way to strap a sitting-baby to a regular chair just using my ergo.
Buckle the waistband at chest height around the baby, then around the back of the chair (obviously, this only works on chairs that have backs). Pull it quite tight, so they are secure. They need to have head control, so this works best for babies from about 6-12mo.
Put the baby's legs through the sides of the ergo, bringing the shoulder straps back around the chair. Secure them together using the chest clip.
And there you go. Baby is secured to a chair, and you are able to eat your meal without a baby strapped to your chest, grabbing your food.
Special thanks to my very adorable model.