Here are two commercials with Yogi Bear and Boo Boo urging folks to not smoke. I think that's Don Messick doing Boo Boo in both but only the first is Daws Butler as Yogi. The second, which was obviously done years later, isn't Daws but with these short commercials, it's sometimes hard to identify the voice actors with great certainty.
Yogi in the second spot sounds like Greg Burson, a student of Daws' who took on the role after Daws left us. Burson, who was a good friend of mine, outlived Daws by about twenty years but still died much too young — in part because of cigarettes…