Having graduated from U Colo Boulder in '75 and having done the Yellow Spur then, and Outer Space relatively recently, I can rate these two.
Yellow Spur in Eldorado Canyon is MUCH MORE difficult and lead out, dangerous and commiting than the trade route on the Snow Creek Wall (Yellow Spur involves some serious wide crack climbing above protection, all of it's pitches are long and real; whilst Outer Space is one of the "Fifty Crowded Classics" for a reason... most of it is hiking).
However, I can recommend highly: Yellow Spur, T-2, Bastille Crack, Green Spur, and numerous easier routes (solo) such as the Redgard Route.
The climbing in Eldorado Canyon is some of the best in the world! The setting, rock quality and general ambiance are not to be missed. Any trip anywhere near this area has to include climbing in Eldo, the Front Range and of course Boulder canyon granite (some of the best anywhere).