The answer to this question depends on your goals, finances and recovery.
A helpful trick is to pull down on the lower abdomen until the skin is tight. If this simulates your desired goal, you may be a great candidate for a mini-abdominoplasty.
In a full abdominoplasty, the skin is elevated to a greater degree providing access to the entirety of the abdominal muscles for tightening. More skin is removed, providing a tighter result and a new umbilicus is formed. The trade-off is a longer scar (generally), more difficult recovery, and additional expense. You will be pulled tight enough that you can plan on 7-10 days in a flexed position day and night after a full abdominoplasty.
A mini-abdominoplasty will address only the skin between the umbilicus and pubicregion, but will help a great deal with the extra skin folded over the pants in a seated or flexed position. A mini abdominoplasty is best for an isolated lower abdominal bulge that is very common after childbearing.
Your plastic surgeon can give you a good idea of which you would benefit from most at the time of the consultation. The full abdominoplasty that she had addressed the upper abdomen and muscle separation to a greater extent than a mini would have.