I am probably in the minority but I prefer cruise then parks. My DH and I sometimes work long hours and after a hectic week of work, packing, and a day of traveling, it's sometimes a bit daunting to have to wake up the next day at the crack of dawn to get to the parks before rope drop etc. Then again, we do like to do power Disney, we like to do as many things as we can, and park hop all over the place! That is just how we do Disney.
When we did our cruise on the Magic this past May, we cruised first then parks. We had such an amazing and relaxing time on the cruise and then we were recharged and ready to hit the parks! Everyone else in our party looked so sad when they had to head back home from port. We're doing the same thing next year - cruise on the Fantasy followed by a week at the parks. I was actually not that sad to leave WDW this year...a) because I knew I had another cruise booked for Feb already, and b) I was so tired and missed my bed! (we had been away for close to 2 weeks).
I can see the draw of parks first then cruise...tire yourself out then a week of relaxation. I will probably try that one year, but in all honesty I may end up sleeping for most of the cruise!