Both are great ships. We've been on Holiday twice and Fascination once. They were both great.
Holiday is older and lacks some of the glitz, but I think she has the friendliest crew in the fleet.
Fascination is beautiful and very well cared for. Her crew was great and we had wonderful time.
Either way, a Carnival cruise is one of the best vacation values around. You will have a great time.
2004 - Fascination
2005 - Ecstasy, Elation
2006 - Sensation, Holiday
2007 - Fantasy, Glory
2008 - Holiday, Sensation
2009 - Fantasy, Valor, Glory
2010 - Monarch OTS