A poll inspired by recent discussions on the sliding timescale and chronologies on the JSA-related threads (not least because JSA # 1's preview seems to establish a 13 year timeline for Batman's career).
I'm talking about what their age range should be in current continuity...not at the start of their careers.
Personally, I'd go for the 40-45 age-range. I think it makes the most sense for all these characters, especially when you take into account the 'generations' of sidekicks, and the ages of Damian and Jon (the latter's chronological age that is).
The way I see it, Bruce's generation is in their early 40's, Dick's generation is in their late 20's/early 30's, Tim's generation is in their early 20's, and Damian's generation are pre-teens/early teens.
I think its possible that some characters from the JL founder generation could be a bit younger, like in their late 30's. But they're all somewhere around 40, give or take a few years.