B.B.
My suggestion: don't drag it out! Most people are happy to go to a shower but don't really want to be there all day long! Once people eat, start opening gifts and serve cake and coffee while gifts are being opened!
One thing that was helpful to me was that my mom bought the thank you cards and placed the envelope in front of every place setting. She instructed everyone to address the evelope to themselves, then she collected and picked one envelope from every table. The person whose envelope she selected got to take the centerpiece home...and I didn't have to address thank you cards!
Oh, and provide alcohol! LOL! I'm kind of kidding, but kind of serious! I love having a mimosa at a shower ;-)