Glad to be of help. I never thought my scores of "useless" Jacksonville info would come in handy.

The beaches there are pretty decent. Nice amount of sand to set up on. Unlike Savannah where we only have a strip of sand and when the tide comes in you have to move everything up to the road. The waves aren't that great in the Jax Beaches unless a storm is coming in. There's a little boardwalk thing around where Beach Boulevard hits the ocean that used to be pretty crappy when I was there. The usual disaffected youth and yuky t-shirt stores. But I understand it's been really spruced up and it's nice now, plus there's the public restrooms down there. I used to live on N14th street and went down to the beach there and it was more quiet. There's a hotel right there. I always figured if I bought a Coke and a sandwhich at the hotel, that gave me hotel bathroom access. Of course, I never asked them their policy on that!

The further away from the boardwalk you get, the less people traffic there is.
If you pull through Savannah, we have a nice scrapbook store. Though I'm sure the family would be very excited to stop just for that, right? LOL It's called Savannah Scrapbooking and she has a great website. You know, just in case you can't make it all the way to Jacksonville without a pit stop. There's an outlet on the way between Savannah and Jax too at Darien. Darien is about in the middle between Sav and Jax. It's bright yellow so you can't miss it. On its own it's not too exciting, but it does have very nice restrooms and the usual fast food, and a Ruby Tuesday. I know with kids it's always good to know where all the restrooms are.
I don't know which side of Jax your friends are on, and I'm sure they'll give you great directions. But I wanted to mention that they were working on the roads around Jax the last time I went through, about two months ago, and we sat f-o-r-e-v-e-r. If it's on your way take the 9A bypass (which is how we go to WDW) to pass to the east or 295 to pass around on the west if you can at all avoid going right through downtown. Plus, 9A takes you over a super cool bridge, and not incidently right past the tre chic outdoor mall Town Center. 9A will also cross you right over all the roads that dead end at the beach if you wanted to let the kids out to just run around for a while (Atlantic Blvd, Beach Blvd, and St. Johns Bluff (St. John's has the least amount of traffice lights of all three))
Way more info than you needed. Have a great trip!
