So I just spent the better part of 10 minutes looking for the official suggestion forum on the WoW website, and obviously I'm an idiot because I can't find it. So I'll post my idea here. I've primarily always used the dungeon finder as a tank, and as such I have no issue with it. My queues are instant, if I want to decline a dungeon in progress, I can just hit cancel and requeue for an instant dungeon. As a DPS however, this is a much more annoying issue. 30+ minute wait times for a dungeon, to have the queue pop and be in progress, on the last boss. Sounds like fun right?
So my suggestion is quite simple, a check box on the dungeon finder window. Something along the lines of "willing to enter dungeons in progress". If checked, you will accept any potential instance group that becomes available, in progress or not. If left unchecked, you might spend another 5 minutes in the queue, but you would ALWAYS get a fresh dungeon. As a DPS, this would save me a lot of hastle.
And yes, you can always get friends to just queue for you and have an instant queue, but really, can someone think of a downside to my idea?