Carl Sagan was an even rarer breed though. More than just popularizing science: making it understandable and curious, he brought it to a deeper almost spiritual level and let you see both how your day to day life was a part of something so unimaginably huge and fantastic while simultaniously making a good case for our species to push the frontiers.
I don't think anyone can compare. If I had to try I'd pick Michio Kaku, he's a definitely more down to Earth than Sagan, but still great.
P.S. For a bit of history and sociology in the mix I really really suggest you pick up Connections (Season 1) and The Day the Universe Changed by James Burke. It stands beside Cosmos as my favorite TV series and will get your kids interested in economics, sociology and history on top of science.