Groundhog Day is easily THE movie that showcases Bill Murray in all of his Bill Murray-ness. Somehow he gets trapped in some time warp where Groundhog Day keeps repeating itself. Upon closer analysis, one sees that he actually goes through a loose application of the grieving process (denial, anger - "don't mess with me, Porkchop!", bargaining, depression, and finally acceptance). When he finally embraces the problem, he learns to play the piano, sculpt ice, administer the Heimlich maneuver, etc. From Ned Ryerson to watching him iron out the kinks in his plans from one day to the next is the most fun you'll ever have.
A television weatherman covering the official groundhog appearance finds his day repeating over and over and over and over.