I still love the idea of making a base level of skills, something anyone can train up to. Then have an apprentice range where you need to quest in order to attain training in that range. An adept level which then leads to a master level. I also feel that to attain the best of something you need to permanently give up the hope of attaining the best of something else.
For example, the skill levels could go up to 50, anyone can train 5 levels of any skill, after that you need to go to the city devoted to that class and complete some quests for them and be initiated into their apprentice program. Being an apprentice allows you to train up to 15 skill level. Once you get that far, if you wish to go further, you have to complete more quests and the guild master formally accepts you into their guild and allows you to train up to skill level 30. To go further you must become a master of your guild, accomplishing amazing feats (quests) and devoting your life to the preservation and advancement of your guild, this allows you to train that skill up to the max. Ideally, I'd love to see a quest for every skill level. Each quest rewarding you with xp and silver (not necessarily enough to train that skill), that xp/silver could always be used to train other class skills, but it unlocks the option to train that skill level for the class that you just quested for.
I would also like to see a similar option for stats. Everyone starts much like we do today, with points to spend and a cap on the starting stats. Not sure if the stat amounts and overall cap needs to be reworked, but I'll use the current system as the example. Anyone has the ability to train a stat up to 70, in order to be able to train it further you'd need to go to the city devoted to the furthering of the stat you wanted to train. And to advance to the pinnacle of that stat you'd need to do individual quests in order to obtain the ability to train that stat another point. Not sure if you should have 30+ quests per stat (to get from 71 through however high we'll go), but I don't think it's too crazy.
I tend toward more quests is better. Not everyone likes to be told what to do, but most everyone likes to have a goal. Even if the goal is to hunt down 5 witches for their ancient mystical knowledge, it's better to have something to strive for than not. I'd also like to see some quests that grant you recipes and possibly the goods needed to make the item. For example, you want a better spellbook, you travel to Cairnopia and the mages have a series of quests devoted to spellcasting, one of which being "Knowledge of the Ice" or something, where they send you on a quest to obtain certain items (a gemstone, book, etc) and when you return they give you nominal xp/silver (assuming they sent you to get 2 of each item and they keep a set), and the recipe for tome of ice. Since you just quested for the ingredients, you have the items and recipe to make a new tome. Similar could be done for mounts, minus the recipe, just "gather the following goods and return to us" then whichever guild it is from uses their generic skills to breed/create/raise your new mount. I'd like to see a guild specific mount, each one has similar stats, but a different special feature.
Of course there would still be random quests and holidays and everything, meaning a ton of quests would be made and that's a lot of work.