Concourses B, C, and most of D belong to TWA; Delta flies out of Concourse A.
There are no major food outlets in Concourse A, just a bar, a newstand and a snack counter that sells water, candy, etc. The closest major food outlet is a full-service Burger King, which is at that same end of the Departure Hall, one floor up from the gates (people who fly in mostly don't know it's there). Most of the main food outlets (Cheers, etc.) are in the area where concourses B and C meet, and along C. There is also a restaurant in the East Terminal, reached by walking all the way through concourse D. Be aware that Lambert has only one double runway, so if there are weather problems we are subject to horrific delays, because there is no perpendicular runway.
With little kids, if your layover is any length, you might want to walk over to Concourse D to let them run around.
(About 10 minute walk.) Most of the high-numbered gates on D are not being used, so the area is wide-open space. I often let my DS run there to let off steam when we are waiting for a SW departure.
If you had a really long layover, you could go into downtown St. Louis and see the Arch. There is a light-rail train that goes directly from Lambert to Downtown for $3, it takes about 30 minutes each way.
