After 11 years as the host of NPR’s “Talk of the Nation,” Neal Conan is signing off. Conan, 68, joined the program in 2003 and has hosted more than 2,500 episodes. During his tenure, he has interviewed a wide range of guests, from politicians and activists to scientists and artists. Conan is known for his thoughtful questions and his ability to draw out the best from his guests. He is also known for his sense of humor and his willingness to tackle difficult topics.