I don't hide it, we still NIP as needed but it's personally really important to me that I support other toddler nursing Mamas in a visible way. I've never had a single comment from a stranger, my family is all about AP and CLW so no probs there, and my IL's have learned to keep their comments to themselves.
I think you should do what feels right to you mama. I think that most mamas who are still nursing at 18+ months just do it at home and don't talk about it much and that's okay.. But it makes me sad to think that people actively shy away from the discussion because our society is just so messed up when it comes to child-rearing.