Seth? He is only good in small doses, would love to see him present, wouldn't wanna see him host a three hour long show for anything.
Kristin Chenoweth is becoming more and more well-known with time. I would say people don't necessarily know her name but they do know her face. Not only did she have a high profile role in THE WEST WING, and earned an Emmy nod for her brilliant comedic turn in PUSHING DAISIES, but she also has done a number of B-movies, and she will be appearing in Reese Witherspoon's upcoming Holiday film FOUR CHRISTMASES. I wouldn't say she could match the star status of a Whoopie Goldberg, Rosie O'Donnell, or Hugh Jackman but she can hold her own. Mostly, I don't think she should host by herself but she would be wonderful with Neil.
If you haven't seen her great chemistry with Neil Patrick Harris, click on this link of the two of them announcing the Emmy nods.
http://cdn.emmys.tv/awards/2008pte/noms_webcast.php
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"