Lots of good ideas in this thread -- as I'm coming in late, I'll sum up my favorites.
1. Teleportation should be in the game; it's intrinsic to most of the genre. The devil's in the details of implementation.
2. Short range, tactical line-of-sight teleport (ala dimension door) is fine at mid levels.
3. Long range, strategic teleport should be possible at high levels, but with some drawback and risk. At those levels, there's not need to force overland travel. The real risk of abuse is the buff-scry-teleport tactic. To balance it, without something as swingy as miss-chance, nor as draconian as "No teleport to an unknown location", I'd make it a ritual with a lengthy casting time (10 minutes or more), which eliminates its use as a tactical retreat tool. I'd also implement a "jump shock" mechanic -- for example, you are stunned for 2+1d4 rounds after arrival. That makes teleporting near a place to attack shortly a viable tactic, but does not make teleporting into combat viable.
3. Infinite range, no risk teleport should also exist -- via fixed-site portals, which can only be built with the highest level ritual magic.
In short, a few tweaks to 3E- and 4E-style teleport magic can fill most needs.
I'm of a similar mind and I just thought I'd jump in too.
I agree there is a place for dimension door, but for me it only works as a limited thing, such as vancian spellslot/day. I don't mind if they prepare it more than once but I don't want large swaths of enemies being bypassed or eliminated, or more importantly DEFENSES being bypassed or eliminated,
routinely or without some effort expended. It the wizard can routinely jump past all kinds of defenses, like several times every fight, then it won't work for me. But that said, that is a large area to maneuver in with a lot of changes that can be made. Oh, I also would prefer a line of effect rule instead of line of sight, but that is just personal preference. Being able to see the destination works most of the time, but if it is blocked by a wall of force or similar kind of barrier then I think it should be a barrier. I see DD as more of a skip or squeeze through the space between, instead of a disappearance in one place and reappearance in another.
As for regular teleport, I love some of the ideas presented here, but I don't like a few of the direct solutions provided. I have some of my own.
For general teleporting, I like the idea back on page 1 or 2:
You can teleport 1 person to a location of your choice in one action.
You can teleport multiple persons to a general location in one action.
You can teleport multiple person to a location of your choice after a hour casting per person.
I think the "2 of 3 rule" can and should be applied to many iconic spells.
But I disagree on the 2/3 and what the third should be. Personally, outside of strong (very high level) magic I think it should be a 1/3 most of the time. Unfortunately I've never felt the time limit aspect to be a good limitation. Either, you have more than enough time, making 10 minutes all but irrelevant to spend on a spell, or they are too long to be used in a crunch when you truly need a teleport spell to get away. Being dazed on landing has a similar problem for me. The only thing the 10 minute casting and dazed on landing do is stop people from scry,teleport,fry,teleport (or variations) but there are a lot of better limiting factors which make more sense. Otherwise those limits don't really matter.
Personally I feel the best limiter is of accuracy. If you are always assured to be off by a number of miles, be that a fixed value of 5-100 miles or a percentage of the distance traveled (which I actually really liked) then that is fine. I feel that should be the
expected outcome instead of the undesired few percent. If you area always out by that factor then it eliminates the scry and fry tactic from the get go.
From there I can understand putting fixes or limits on it. Like if you have never been to a place then the distance out changes as well, you don't know exactly how far you are from your target, or in what direction. You could be 80 leagues from the place you meant to be or you could be the next street over. That is assuming you don't know where you are going, if you DO then the miss chance could be lower. If it is your childhood home where you spent most of your life then I could see appearing at the outskirts of town, or a field where you used to play, or (if you are lucky) right inside your old bedroom. But once again, for me it makes a lot more sense if you are NOT expected to land in your room, that you are ALWAYS going to be off target, but aren't sure how much.
Adding more weight, more passengers and similar aspects from previous versions of teleport should be MORE factors (or higher degree of being off target).
Next, if there is no safe spot EXCEPT the spot you are aiming for, such as a single room in the middle of a solid stone mountain, then I want the spell just not to work - instead of the silly rules of being buried or shunted to the next free space. I don't really want my players trying that at all, unless they have something to hit, not because they could die from doing it but because it is all but impossible -the spell fails.
Now I've said a couple of times that I think you could have something to hit, or aim for. That is where teleportation circles come into play. If you are trying to hit a location and that location has a teleportation circle then ignore the miss chance for being off target. DMs can decide how hard, or costly, or time consuming it is to make these circles. I would want big elaborate stone circles with intricate carvings in order to make the circle work properly, others may want something simple involving special salts or whatever and that is fine too. But that would be my number one way to consistently be on target.
Also, for my money, if you are teleporting FROM a circle then you can ignore issues of carrying limit or party size (passengers) when casting the spell. Because then it isn't like you are doing it constantly or often, it is only when you happen to find these circles (or make them).
Also, in general, I don't need the circles to be linked per se. I can understand them even coming with a lock to ensure unwanted travelers can't use them. (The lock could be a key, item, soil, passphrase, etc. used at the time of casting TO the circle before traveling or arriving.)
An honourable mention to the whole "have to be invited thing" or passing the threshold which I would institute as a general rule as well, but I think that a lot of what I've proposed further up solves a lot of those problems.