Yup, if you buy your tix close to departure early boarding doesn't get you in the 1st group...but if you didn't buy it you would be at the end of the C group.

We usually buy our tix early and RARELY get above A30. I think it is worth it....and I agree that SWA would not be a last minute choice for flying since you will be VERY disappointed with your position in line

Families with kids do not get pre-board status before the A group...