That sounds good. Making skills more valuable, and able to really scale with level compared with spells, would actually make the skill monkey role valuable. Maybe just slap a restriction on how high your level in skills can go, such as-

1-3: C
4-8: B
9-14: A
15-20: S
Maybe. Easiest way to describe it would be allow max ranks invested in a skill equal to level + 2. So you could start with C rank in a skill by investing 3 ranks. You'd hit B rank by level 4, A rank by level 9, and S rank at level 17.

Random thought:

Skill Focus
Prerequisite: At least C rank in one skill.
Benefit: Choose one skill you have at least a C rank in. You gain a +3 bonus to rolls involving this skill. Additionally, you may attempt a check against a challenge 2 ranks above your current skill rank, with a DC of 25. Gain 1 extra Skill Trick that requires the chosen skill.
Special: This feat may be taken multiple times, its effects do not stack. Each time you take this feat, you choose another skill you have at least C rank in, and gain the benefits with that skill as well.

Given the range in DCs are now much smaller, that +3 bonus is actually worthwhile (equivalent to getting +12 in the linked attribute), and being able to attempt higher level challenges could be useful for the first half of the game. The extra skill trick makes sure it's still useful at higher levels.