I have met a lot, actually. We stumbled into a leonberger picnic a few years back. I believe there were 26 dogs there but a couple were Newfoundlands/Landseers. They are a very gentle breed, very smart, beautiful, friendly....
Those dogs REALLY impressed me to the point that I might get one one day if I'm in the place for a giant dog. (It will be a LONG time) They do have a short lifespan like most giant breeds, so I'm not sure how I could handle the heartache.
ETA: Btw, the picnic we came across was when we lived in Houston.