D&D magic is surprisingly flavourless in many ways. It's always reliable, it almost never costs the spellcaster any effort (other than the time it takes to prepare the spell). It tends to be treated as just a list of, y'know, stuff this dude can do once or twice a day. I guess my gripe is that it just feels too convenient, rather than Meddling With Forces Mortal Man Ought Not To Wot Of.
Now as far as playability goes, that's OK. If you make magic-use too dangerous or difficult, people will just choose not to play magic-users. However, there are a few areas where I believe a bit less convenience can make for more fun and interesting game play, and the area of detection spells is one of them.
To that end, I've rewritten them. Pretty nearly all of them — detect evil, detect traps, detect booty-call, etc. — follow the same pattern as detect magic, which I present below as an example:
Components: V, S
Casting Time: 1 round
Area of Effect: 60’ cone
Duration: Concentration, up to 1 round/level
Saving Throw: None
Magic Resistance: No
You detect the presence of magical auras in a 60° cone up to 60’ long, within your line of sight.
Although the spell will alert you to the presence of magic within that area, it does not specify which object, if any, is actually magical.
If you continue to concentrate on the same area, the second round of concentration will give you a direction to the most powerful magic source in the area of effect. A third round will give you both direction and range to within a 5' diameter area of the most powerful magic source, OR you can discern the direction to the next most powerful magic source. Successive rounds of concentration will allow you to home in on other magic sources within the area of effect.
To focus on a specific object, you must actually be touching it, though if you have narrowed the detection down to a 5' circle, and there's only one object in that area, it might be safe to assume that that object is the source. Then again, it might not.
You may turn to face another 60°, or focus on another object at hand each round.
This rewrite makes detect magic less easy and convenient, but it doesn't really fundamentally alter the workings of the spell. You can still isolate magical auras — you just have to take a bit more time over it. Of course it does make the spell a lot less useful for 1st level magic-users... but screw them. Wimps.