Before I give my opinion, my DDB girl has been extensively socialised and attended well supervised doggy daycare daily for over a year. She knows how to play with a variety of dogs from Chihuahuas to Danes. While reactive dogs don't really bother her up to now, I don't want that to change.
I won't take my girl to dog parks outside of training time any more. Either she will bound up to dogs to play (play bow followed by rolling over to show her belly) which freaks out other dogs, presumably due to her size so they bark and lunge at her... or, other dogs run for her and won't quit going for her. If anything happens, my girl will be blamed due to size etc... I've noticed that a lot of people who can't be bothered to properly socialise their dogs take them to dog parks and let them run around either terrorising other dogs, or being freaked out and reacting badly to other dogs. Avoid them.
We have a training group and take our pack to the beach every so often so that's enough social interaction for us.