I also had trouble with creating a spell point system as I saw the un-balance high level casters could cause, by using all their spell points to cast dozens of high levels spells. But then the very system I was trying to get rid of gave me the answer I was looking for: Limit the number of spells per spell level per day the caster can cast.

With a scaling limit the caster still has the flexability of the spell point system, but can't just dump all his points into high level spells. And having to keep track of the # of spells per spell level you have used is the same as what Sorcerers have to do with the "Fire & Forget" system anyways.
The following is an example of the limits I came up with for Wizards(I have yet to try this out yet :\ )
Maximum number of spells per spell level per day*
0th/1st/2nd/3rd/4th/5th/6th/7th/8th/9th
∞ / 4 /
∞ / 5 /
∞ / 5 / 4 /
∞ / 6 / 5 /
∞ / 6 / 5 / 4 /
∞ / 7 / 6 / 5 /
∞ / 7 / 6 / 5 / 4 /
∞ / 8 / 7 / 6 / 5 /
∞ / 8 / 7 / 6 / 5 / 4 /
∞ / 9 / 8 / 7 / 6 / 5 /
∞ / 9 / 8 / 7 / 6 / 5 / 4 /
∞ / 10 / 9 / 8 / 7 / 6 / 5 /
∞ / 10 / 9 / 8 / 7 / 6 / 5 / 4 /
∞ / 11 / 10 / 9 / 8 / 7 / 6 / 5 /
∞ / 11 / 10 / 9 / 8 / 7 / 6 / 5 / 4 /
∞ / 12 / 11 / 10 / 9 / 8 / 7 / 6 / 5 /
∞ / 12 / 11 / 10 / 9 / 8 / 7 / 6 / 5 / 4 /
∞ / 13 / 12 / 11 / 10 / 9 / 8 / 7 / 6 / 5 /
∞ / 13 / 12 / 11 / 10 / 9 / 8 / 7 / 6 / 5 /
∞ / 14 / 13 / 12 / 11 / 10 / 9 / 8 / 7 / 6 /
* Specialist add 1 to the listed limit of spells per spell level per day, but extra spells must be from specialist school.