Amen, especially since it seems like since .85 that all improvements take much longer to build.  I keep having to clear my building improvements before the finish so I can build some troops.

It isn´t also realistic that a big city build one building after another or that you can´t train multiple troops at ones. But its a game.

I think that the one queue is perfect. I have to choose between city improving or warmongering. Its sometimes a tough choice, but thats exactly what it should be.

To me, a single queue represents the fact that the town puts all its efforts into completing something. That makes perfect sense.

Just make it possible to reorder the queue.  Or at the very least, as malekith said, let us insert to the front of the build order

Having a single queue is critical to having a balanced game IMO. As Sarudak said it makes the user choose between building their economy or building their military. If you give the player two queues they will do both simultaneously which removes one of the main strategic choices in a good strategy game.

I think its important to be able to halt a building production while not taking away all those turns ...

being able to mix up the build order (as has been done by Civ et all) would be a good place to start.

Yes, I'd like that too.

Allowing queue management within one production queue is the way to go.