Well.......
We actually planned several months of promotional activity prior to go-live.
We held competitions - decorating the workfront logo that we printed out poster size - naming the Workfront admin team (we are now called PAWS) - best avatar in WF - picture lion quiz - to name a few
Prizes were general 'Lion Bars' - not sure if you're familiar with those but they're an English chocolate bar.
We had a 'play day' where users could drop in to 'play' with workfront before go-live
Pre launch week we had Pizza on the friday for the whole dept and launch week we had cake at the end of the week to celebrate.
That's all I can remember off the top of my head but launch and adoption we really well.
You will always have people who will drag their feet and push back on Workfront so we believe that adoption promotions should be ongoing.
Hope this helps, let me know if you have more questions....