The IP system feels like a grind
We've seen the calculations all over reddit. If you want all the champions and some runes it takes thousands of games.
The double IP Weekends seem to be a good idea but more can be done to balance that system. Maybe Spin to win/Wheel of fortune with the rewards stacking up the more often you login in a week. This would give tier two runes but a shit-ton of them that can be combined for T3 Runes. Perhaps rare champs and/ or even RP to continue to entice people to login each and every day.
Another solution would be to give IP, Runes and Champions as players level up to 30.