If the Reds could find any way possible to trade Griffey (even if it means eating some of his contract), my personal feeling is that it would be for the best. Send him to the AL to a rich team that can afford to take a chance on a high risk/high reward slugger and allow Pena to play CF even though it's not his natural position. A young OF of Dunn, Kearns, and Pena is awfully impressive, and I personally think Griffey would get more in a trade anyways if you eat some of his contract. Pena's trade value is going to stay pretty low until he can prove he is able to hit at least slighly for average, which he won't be able to prove until he gets playing time.
Kind of a bad situation for the Reds...although having a "backup" like Pena is exactly a bad situation I guess.