After a while I tend to run out of buildings to build in my developed cities.  So then I can crank out as many units as I want.

For me, both ways work fine. I wouldn't mind building two things at once (maybe at a higher cost or longer production) but the "one-at-a-time" building works fine too.

Personally, I think I'd prefer multiple production...

Big, fat, hairy "No!"

If you're gonna have more than one, might as well have 75.

I agree to having two queues.  I continually need to remove and readd all my buildings just because I lost a unit and need to build a new one and move it to the top of the queue.

I like the single production queue, but there should be a rearrange queue possibility and something (not only one (?) building) that benefits from an empty queue...like a little more money or research based on production strength.

I like the single queue better.

Hmm, good arguments on both sides.  The whole "realism" says; why not have some people building buildings, while others produce troops, all in the same town, but some people feel "game play" is better when you're forced to make hard decisions between one or the other.

I can think of a compromise or two; 

A) Make it an option at the start of the game (one building queue or two).  This is by far the hardest I would think, because the AI would be required to play intelligently both ways, so there would be a lot of effort involved with this decision)

  Bring back the two separate production lines, but make there be a production penalty if both are running at once (like James009D mentioned).  If you really, really needed a building or some troops fast, you could hit a "pause" button on the other type of production, to get what you needed produced at full speed again.  It still makes for interesting choices, and to be honest it really does feel a lot more realistic. 

C)  Keep one queue, but somehow keep track of what a city has been producing, either buildings or troops, and give a small but accumulating bonus to the OTHER type of production, that will go away once something of the other sort has been built.  The bonus shouldn't appear after creating either one building or one unit, but rather after perhaps 3 either bildings or units in a row.

Say for example that city A has produced 4 different buildings in a row without building any troops.  It could now have a + 20 % to production for the next troops it produces.  If the player build another building instead, the bonus could grow up to 30 %. 

This would represent the fact that even though you haven't REALLY been building any troops, the city has been "training" some guys in the background.  If it was done the other way (producing a lot of troops, and now you have a bonus to make a building), it could represent that there was some work being done on the building "in the background" while the city was focused on producing troops. 

Anyway, these are just some of my ideas.  I really like C, but i don't think it would work well in this game, it would probably work a lot better in a much more complex game that really focuses on economics (like some of the WWII games I have played, can't remember the names right now).

Yes, I realize that all of these ideas would make programming the AI to play intelligently even harder, because the AI would have to be taught how to intelligently take advantage of the system.

Also, I definitely second the idea of being able to reorganize the queue.  It's a very important function, for lots of reasons.  It's one of those polish things;  if that ability isn't present, I know somebody somewhere was being lazy.

<edit:  Whoops, idea "B" is a chillin dude.>

What you call fun, some people call frustrating.  It seems kinda silly to me that, because my town was building a watermill, NOBODY in that town was practicing how to fight with a spear and wear armor and move as part of a formation?  EVERY single person in that town that wasn't "off gathering grain and materials" was either building that watermill or sitting on their butts?  In a land where monsters roam up out of the woods and attack and destroy towns?

Also, having more queues to manage is dumbing the game down?  It changes the strategy, but I think a lot of people would feel it makes the game more complex, because it is one more thing to manage.  Yes, it takes away the choice "defenses OR city progression", but that's just one choice out of a lot in this game (though it is, admittedly, a big one).

Both approaches have their strong points and weak points.  It's a matter of preference.

I prefer one queue.

I don't have any problem with having a seperate queue for each barracks you build in town, since each one could be training new troops.  Just like you could have multiple building queues if you had multiple construction groups in the town, although that is a bit less likely.  It doesn't make much sense for the trainers to sit on their thumbs while building construction is going on, just like it doesn't make sense for the construction workers to sit on their thumbs while the troops are being trained.  The two have nothing to do with each other, so why are they linked in a single queue.  It makes no sense!

Still being able to build more at the same time doesn't dumb anything down.  You can buy all you want at the store, and yet you don't go out there and buy thousands of dollars worth of stuff everytime you go out.  You aren't likely to be able to afford all that stuff, and you probably couldn't fit thousands of dollars worth of groceries in your trunk, plus you probably couldn't go through it all before some of it went bad.  The ability to do so, doesn't change the fact that you really have to plan out what you do, and when you do it.  I feel the single queue is a cop-out, and it makes the game easier for both the player and the AI.  But it is the AI that I feel will keep them from changing it even if most people supported it.

I think the single queue is better, because the player has to make a choice.