3 weeks at Disney....how awesome!!! If you don't have kids, I would plan an evening to see the Cirque show, also plan an evening to hit Pleasure Island...
Since you will be there for some time, you can take each day slow...enjoy everything! See the shows in the parks...you could even venture out and see the rest of Orlando...DH and I are going to SeaWorld on our May trip...we did Universal on our last trip...you could always see the other parks....for me, this made me appreciate Disney more...all the hard work and research that goes into their rides!