You can also get rid of idle chat if you are using Scumbumbo's SCAM (Self configuring autonomy mod) by turning the autonomy off on it.
But honestly, idle chat doesn't seem entirely like what people here are talking about fixing. Idle chat is the empty babble in between actual social interactions that does nothing for relationship (it's called that in the game programming). It's like the pauses between bites of food. What getting rid of the idle chat does is make sims only use real interactions with no empty chatter in between. That won't change sims approaching you, just what they do WHEN they approach you, so it won't start with idle chat but with a real interaction. Which is usually an introduction social if they don't know you, since they need that first before they can use others.
The problem lies more in the queue itself, I think. The interaction the new sim wants to do with you doesn't always show up right away so you can't cancel it, especially if you are already talking to another sim. Which means the only way you can get rid of the far away sim that is making your sim just stand and wait is to cancel the conversation you're already in. If there's anything they need to do, it's to cut down on the distance a sim can try and interact with you from, and to make the little picture on the top where it shows who are you interacting with clickable, so you can just boot them out.
Another thing you can do is to turn off autonomy (with a mod) on introductions (along with nuking idle chat), if you don't want sims you don't know interacting with you. They will still come up and talk to the person you are talking to if they know THEM, but they will leave you alone.