Q Will some Champions be free more often than others?
A Yes, because some Champions are simpler to play that others, and our first goal with the free Champion rotation is to allow new players simple Champions to try for their first games.
Personally, I think every champion should spend equal time in free use.
Sure, have a few easier ones every week, but rotate them so they spend the same amount of time.
And why just focus on new players? Some more experienced players who don't buy RP, but just earn IP for champions, therefore they may not have many, may want to try something new and challenging. So you should have some champions that are harder to play every week as well.
As far as people asking why the new champions aren't free the first week, I agree that they shouldn't. LoL is a great free game and some people are getting too greedy. When a new champion comes out people would like to try the champion right then, and buy it. If they could try it for free, why would they buy it? Then you only get the people who fall in love with the champion enough so they buy it...
Just my opinions...
Love you Riot!