That's basically the kind of stuff we do.
We're building a leprechaun trap tonight with Dad, and then the leprechaun plays tricks throughout the day - not just overnight. So during the day..something big might happen when no one was looking.
With the trap, we just decorate a shoe box, put the leprechaun's hat underneath, and try to capture him through the day - sometime in the evening, the trap gets set, the bells go off (we have some shamrock garland hanging on the fireplace that has little bells go off and we make sure to jingle that), and the boys come running to find some gold coins, skittles and a little trinket for them from the leprechaun.
This year, we'll probably do the rainbow cake as a treat for Aiden, and do some cooking to reinforce our math stuff (Irish Soda bread is probably going to be it since it's fairly easy and we've got a busy day/night).
Something a friend of ours does is put a gold chocolate coin with each 'trick' the leprechaun did, and the kids can have fun all day finding little tricks and treats.