I'm definitely a fan of having different types of locks. Picking a deadbolt isn't the same as picking a set of handcuffs, after all. Making it abstract will work well if the game is otherworldly, like a futuristic sci-fi lock or a magical dwarven lock or something, but having a block-sliding minigame to see if I can pick a conventional tumbler lock would feel very strange indeed. I don't think I'd like that. I'd rather just have a progress bar.

One thing I've been thinking about for a lockpicking minigame is a tree system. It's like a brute-force combination breaking system, but dressed up a little bit. Here's the naked mechanic:

Have the combination for opening the lock consist of four digits between one and three. That's 81 different possibilities, so it'll take a long time to get through them all. Players can get good at mashing the buttons to speed things along, and character skill can help out by verifying a correct choice on one of the numbers, effectively reducing the complexity of the puzzle by 2/3 for every level in the skill. So you put in 1-1-1-1, 1-1-1-2, 1-1-1-3, 1-1-2-1, and on and on and on until it pops open. When you get better, you can test the first digit individually, so you'll get it in three tries max, leaving you with no more than 12 tries for a lock, instead of 81. Here's how you dress it up:

Your guy kneels down by the keyhole, stick his picks in there and you've got three buttons to hit. One is a sort of prodding motion, one is a twist, one is a rake. You flail wildly against these buttons until the thing opens. With character skill, you'll be able to "feel out" a given tumbler and solve it before moving on, so your picking will become more deliberate and efficient. You don't need a little window to come up showing the lock's innards, you don't need an on-screen prompt, just a character animation and a few different sound effects to convey the needed information to the player.

Anything that requires mouse control precision. You can take ideas from "mouse maze" games, where you move cursor to not touch walls.

Here it can be setting a set of tumblers with lockpick to a very specific height, provided beforehand by rules, and pushing button, all under time constrains. Failure to meet time constraints may reset the puzzle and do something in the outside world, like alerting guards. Pressing button before all tumblers are in their very specific places may break the lockpick.

How about keeping it simple but suspenseful at the same time. When you click on the lock your character goes into a lock picking animation. The skill comes from not being detected by the roving npcs time it wrong and you risk getting caught. Whether or not you also incorporate the whole thing of lock picks breaking is up to you. I also think your skill should lvl up the more you use it. So you can for instance break a simple lock in a few seconds while more complicated ones might take a minute or too. You could also have some distraction special abilitys that could be incorporated. Anyway just a few ideas.