So err, hate to point out the obvious but putting it at a higher exp rate and calling it "high" rate isn't going to solve anything.
Because if you do so and make it easier to level, you need a LOT more content. I mean loads.
The reason high rates are fun isn't because it's faster to level. It's because you're going through so much new content almost all the time. That's what it means to be a high rate.
If you're not prepared to do this, don't bother making a high rate.