Check out the Pea Ridge website before you go (http://www.nps.gov/peri/home.htm). It should give you most of the info that you'll need about the battle. Give yourself enough time to watch the orientation film before you hit the battlefield. Keep in mind that this was a winter battle. Most people forget that as they're dying in the heat & humidity. At the Leetown battlefield (stop #3), most of the fighting was in the woods, not in the open field. There's a battery next to the parking lot facing NE towards the woods. That is where the major fighting was.

Dale's right, if you have the time, Prairie Grove is a really great battlefield. The visitor center is a bit outdated, but the tour road and the field itself are terrific.

One other thing about Pea Ridge, and I can't stress this enough. Bring heavy-duty bug repellant. THE TICKS ARE HORRIBLE. If you get off the mowed areas, you're going to get covered.