Skill Challenges should be given as much space as a combat encounter of the same difficulty. More detail to each would make them much more interesting. The particulars of each encounter should be kept from the players, but I still think the players should have the basic rules to work from.
Totally with you on the first point.
I have mixed feelings about the rest. A lot depends upon what you value most in the RPG experience.
Gamers want to know the rules so they can find the opportunities to squeeze out great performance in their characters. The encounters can become as engaging as combat if the complexity and variety of choices they have to make are roughly equivalent to the choices they get to make in combat. In combat, a player chooses where to move to, how to get there, how to avoid dangers along the way, what to do when he gets there, which attack to use, and even though the dice randomize some results, the player has a good idea what his odds of success are and how he can improve those odds (make sure you attack with combat advantage, etc).
So long as combat has those sorts of granular, interesting, specific choices, and exploration and roleplaying encounters don't, the non-combat encounters will never be as interesting to the gamers.
Story-focused players see all the superstructure of game mechanics into the non-combat scenes as distractions from the the part of the game they value most, and for which they tolerate the combat side of the game.
If you've got story-focused players, but as a DM you like the structure that a SC system gives you for running non-combat encounters, you probably don't want to share the details with your players. If your players are gamers, you're going to want to lay those structures and rules out front so they can play the game.
And, of course, we all have both kinds of players in our groups, and each of our players is somewhere on that continuum, and is not just one or the other. (Except for a couple of the guys in my game, and they know who they are.....)
All of that is just to say I don't think there's a single right answer for Skill Challenges -- and maybe that's why Next, with it's modular, make-the-game-you-want-from-these-building-blocks approach will actually be the right way to handle these. And it could be different
every single time.
Here's what I mean: Classic Skill Challenge-type Application: Chase Scene.
Some chases are simple things, like a purse-snatcher in the opening of a Law & Order episode that accidentally leads the party to a dead body. The chase doesn't matter much in the game and you don't want to spend a lot of time on it. A quick set of opposed dex checks might be enough to settle the scene.
Some chases are the whole story. Like Smokey & The Bandit. The players are going to need to make complex checks, solve complex problems along the way, feel the pressure of the Smokey on their tail, and make vitally important tactical decisions about the chase as they go. And, in a couple of weeks, when I decide that the next session will be Smokey & The Bandit II - I'll want to try out some different mechanics and ideas to keep the game fresh. So even these two macro chase challenges will be different from each other, and that's great.
We need a system that will let us build both, as we need them, and that won't tell us that either is the "right" way to do it.
-rg