My Perfect School: Houses v. Classes

At my high school some of the best moments I remember were spirit weeks and pep rallies.  We really one had two a year:  one during fall sports and one during winter sports.  During spirit weeks we would have class competitions to earn points.  The same would be true for the pep rallies if you won a game you won points for your class.  The class with the highest points at the end of spirit week would then possess the school mascot for the next semester.  My class (Class of 2000 -- Represent!) won it three semesters in a row our last three years at the school.  This is a system I would like to incorporate in one of two ways:  by Multi-class Houses or by graduating Classes.

Here is the deal every quarter or semester the groups would have various spirit days, and other competitions.  Spirit days earns you points for "dressing up" appropriately for that day.  One competition I have thought of is an intramural competition of sports.  Each quarter would have a different sport and the classes would compete against each other kind of like the Quiditch Cup at Hogwarts in the Harry Potter series.  Each win would earn you points for your class.  At the end of the quarter or semester you have the pep rally with more class competitions.  Another competition could be like a quarter long scavenger hunt or something else like that.  At the end of the quarter or semester you would have a pep rally with more games that earn a grouping more points.  The group with the most points at the end of all the competitions wins and possess the mascot until the next grading period. 

Here are my areas of which I want input from my readers.  Should I do this by graduating classes or by a house system?  I like the graduating class system because that is how we did it, but you can't really establish long trains of wins.  Also it is more favored to the upper class men than the freshmen.  The House idea would be cool where each house has multiple students from each grade level.  They would be assigned a house at the start of their time in the school and remain in that house during their tenure at the school.  I am not sure how we would select for each house.  The key would be to key the houses as equally proportioned as possible in total numbers and in the different grade levels in each house.

I would like my readers comments on this posting.  Please give me some help.  Which one should be used:  Houses or Classes?  Thanks in advance.