What kept it interesting is that the nature of the competition changed from one round to the next. The hero had to participate in a grand melee, run a mechanical gauntlet, capture the flag in a team melee, enter a joust, team up with another finalist in a tag-team match, and finally compete in single combat. The first five rounds were abstracted as skill challenges, while the sixth round was a combat encounter.
I've edited my session notes for the tournament and formatted it so that it will be easy to use in your own campaign. While it was written for use with 1st level characters, it would be easy to adjust the level of the challenges. It should also be easy to adapt the framework to other editions of D&D or even to other similar game systems.
You can download a PDF containing my write up of the tournament here.
I hope this stock medieval tournament can be useful to you. As ever, your feedback is always welcome.