Workarounds for Demihuman Level Limits

I’m behind on the curve a bit here, I know this was the topic du jour a bit ago, but it was raised by one of my players recently, so it’s been on my mind a bit.  While I understand the reasoning – you’ve got to give players SOME reason to play a Human, it just doesn’t make sense, especially in the context of the long life spans of the demihumans.  How does an elf, that lives for thousands of years, never progress beyond 12^th level clerical abilities?  How do they never get better than a 12^th level fighter?   It just doesn’t make sense.

Now mind you, I’m going to discuss this within the confines of 2e, as that is the game which is presenting me with this problem right now, but I think some of the possibilities could be applied to other games, as well.

The 2e DM’s Guide provides two optional rules, one I like better than the other, and I’ve come up with a third idea.  I’d love to get some feedback before I pitch the ideas at Wednesday’s game.

Option 1: Attribute Based Level Advancement

This gives bonus levels based on the score of the Prime Requisite Attribute.  On a 14 or 15, the demihuman can advance one level beyond the limit.  With a 16 or 17, they can exceed by 2, an 18 gets them 3 levels, and a 19 gets them 4.  For many of the races, a 19 attribute score gets them up to level 19, which is comparable to a human, and there is some attraction there.

Option 2: Slow Advancement Beyond the Limit

When the demihuman hits the limit, they continue to advance, but the requirements to advance beyond the level double.  It allows them to reach the same heights of power as the humans, but it takes much longer to do so.  This almost makes sense, too, in the context of their long lives.

Option 3: Dual-classing Multiclassed Demihumans

When the demihuman reaches the level limit for their chosen class, they can pick another class to advance through.  Their THAC0 and saving throws hit points and such progress at the rate of their current class.  Again, this make sense, when you consider their lifespans.  This is basically 2e’s approach to Dual-Classing for humans.

Any of these are better than 2e’s Multiclassing system, which involves proportional distribution of bonuses, hit points and experience points, and all sorts of nonsense that takes 2 pages to explain.  

Any other ways of doing things?