I can't give specifics on lighting, cause that's something I'm not an expert on. However, darkening the bg didn't do you any favors, as the subjects blend in with it. There should be good visual seperation between subject(s) and bg. Are you using the pop up or a speed lite? Of the bunch, I think #1 has the best feel to it, looks rather spontanious (sp?) and shows nice interaction between mom and son. The rest of the poses are kinda typical commercial family photog. White was probably not the best color for shirts, I would have gone for some color, something light or midtone. All of these could use a contrast bump in post, and definately some sharpening. Start playing around in Av and manual as well, getting away from the presets will give you control.