Reflections on leveling a shadow priest

Having grown bored with all that end-game has to offer my druid and having temporarily lost interest in my long-suffering shaman alt (I'll find him interesting again at some point; my interest in him ebbs and wains) I have turned to the dark side, rolled a priest, and spec'ed him shadow for leveling (get it?). I rolled him simply because I was getting bored with healing as a tree and I wanted to try a new healing style. Neither the shaman nor the paladin healing style particularly appealed to me, so the priest was the logical decision. In leveling my priest, I have learned a few things that I thought I would share with you.

Leveling an alt is easier when you have goals for that alt and they are reasonable.
What surprised me the most was how dedicated I was to this alt. Most of my alts never get past level 25 (my shaman being the notable exception, currently at 62), but my priest is currently level 30 and still going strong. In fact, he is the first character I have leveled mostly without any rested state. What made him different? Probably my goals with him. I rolled my shaman mostly with the intent to have fun, which is why I have stuck with him. I rolled all of my other alts out of class envy and leveled them with the intent of using them in group-play in the back of my mind. However, that was such a far off goal I never stuck with those alts. With my priest, my goal was to get him to 40, buy dual specs, make his other spec holy, and start healing dungeons. A much more reasonable goal, aye? Since my end-goal for my priest isn't as far off as my goals for my other alts were, I was more motivated to level him. The larger lesson is that if you role an alt for fun, focusing on how you will use him at end-game will make you less motivated to play it.

Leveling an alt is more fun when you take two gathering professions.
My priest has skinning and herbalism, but if he actually reaches a higher level, I'll drop skinning and power-level alchemy. Why herbalism and not mining? For Lifeblood, of course; that ability has saved me quite a few times. Why not level alchemy now and save myself the hassle? A few reasons.
1. Selling all those herbs and all that leather on the auction house makes my alt filthy rich and able to stand on his own without injections of money from my main.
2. Leveling alchemy would just be another thing to do and would distract me from questings and leveling in general.
3. Leveling a profession now so I don't need to do it later causes me to think about the future too much, and though having reasonable goals for an alt makes him easier to level (as I said before), the easiest way to stick with an alt is to focus on the here-and-now and not think about the future.

Shadow is not a very attractive leveling tree.
Now, when I say that shadow isn't attractive for leveling, I don't mean that it isn't viable or fun; it is both of those things. However, when a priest first starts out, he can cause more damage with Smite and Holy Fire than he can with Mind Flay and Mind Blast. Throw in the DoTs for added damage and leveling holy seems like a good idea. Thing is, Mind Flay and Mind Blast have many talents that improve their damage and mana-efficiency, but Smite and Holy Fire don't have as many, and priests that spec holy won't take talents that improve those abilities. Smite and Holy Fire are supposed to allow healing priests to be able to fend for themselves, so they need to have high damage to be viable. However, that means that at low levels, shadow doesn't do as much damage as holy, which is just not right. Perhaps increasing the damage of low ranks of Mind Flay and Mind Blast (and increasing the damage they cause at lower levels once ranks are removed) could solve this problem. Speaking of which...

Ability ranks need to go, now.
Ability ranks are going away with Cataclysm, but they need to go out the door right now. As it stands, all ranks of spells cost the same amount of mana. This means that as you level, each spell gets less and less mana efficient until you can purchase the next rank. On my priest, this resulted in Mind Flay, which is supposed to be the pinnacle of mana efficiency, being my least mana-efficient ability during the few levels before its upgrade. It also caused the least amount of damage, so I had no reason to use it at all. Having all ranks of spells cost the same while still requiring that their damage be upgraded every few levels simply doesn't work; it needs to end now, before Cataclysm comes out. It can't be that difficult to implement, so why delay such a necessary fix?

Have you learned any other interesting lessons by leveling alts?