I've obly participated, not run, but your family could get the buzz of hanging out at the start, watch the elite start etc, then get on the metro to the finish and get a good place along the seafront at South Shields. Then get metro back into town again at the end.
BTW, it's crowded everywhere. Well, it's the biggest running event in the UK (bigger than the London marathon) 35000 + runners so nowhere will be exactly empty. It's very easy to miss each other, see it as a bonus if they spot you and decide whose surname you'll be meeting at, at the end. (it's divided into letters eg K/L, so don't do what we did the first time which is leave it unclear whose surname letter was in fact the meeting point!).