Organising and grouping cities

[LegendSD]

Once you get later on in the game where you have 50+ cities it starts getting very hard to organise and go through each of your cities. So I was thinking maybe some sort of way to group cities, a bit like forums I suppose, so you could for example, make a group for each region, so you put all your cities in one region, say R21, into one group and another group for R42 ect ect. Lots of players also have defence and attack cities so you could group them In this way too. I feel this would work best if we could organise and pick which cities go in each groups ourselves.
What do you think?
I feel it would make the game much easier once you get past the first month or so.
Thanks
Legend