I blogged previously about the need for a proper, joined-up local government reform process in Northern Ireland. To summarise, councils should be both larger and more powerful in order to be worthwhile, and the traditional counties would provide a foundation of legitimacy. As an addendum, here is a map I made of my preferred model based on electoral wards, following a recent discussion on Slugger. Please note these boundaries are indicative only, and would of course be subject to local consultation – the boundary around Dromore in particular would require some tweaking at the townland level.
Performing a napkin calculation based on current council areas, we get:
BELFAST ~ 350k:
Belfast, Castlereagh (minus Carryduff and Dundonald) plus bits of Lisburn
ANTRIM ~320k:
Ballymena, Ballymoney, Moyle, Larne, Carrickfergus, Newtownabbey, Antrim plus Glenavy.
DOWN AND LAGAN VALLEY ~330k:
North Down, Ards, Down, most of Lisburn plus bits of Castlereagh, Banbridge and Newry&Mourne
ARMAGH AND UPPER BANN ~290k:
Craigavon, Armagh, most of Newry&Mourne and Banbridge
TYRONE AND FERMANAGH ~250k:
Cookstown, Dungannon, Omagh, Strabane, Fermanagh
(LONDON)DERRY ~250k:
Coleraine, Magherafelt, Limavady, Derry City
Urban, eastern councils will be slightly higher in population and lower in area compared to rural, western ones. Drumlins Rock suggested that Belfast should be expanded further to take in Dundonald, Holywood and Newtownabbey, however I have not shown that here as I feel it is an argument for another time.
The random ramblings of andrewg 
Andrew
This certainly looks sensible. It’s timely again as RPA rumbles on and as the south moves to a model of county councils and municipal districts. Have you projected council votes into these areas? If you have how did the votes breakdown? What happens to Belfast? I wonder would nationalist parties be able to accept your proposed boundaries for Belfast? There certainly wouldn’t be much credibility to accusations of gerrymandering but the symbolism of a balanced or nationalist Belfast might be more important than bureaucratic tidiness. .
As you say NI wide decision may be needed for contested matters such as flag flying but if we want to move onto bread and butter issues at council level we need to trust them with some bread and some butter. We have 7 PSNI areas, 6 regional colleges, 6 Health and Social Care Trusts. We clearly keep reaching similar decisions across departments concerning economies of scale, effective areas and spans of control so why not establish oversight at the same level?
I haven’t done the numbers, but I suspect it would come out at 2+2+2: Two Unionist (Antrim and Down/Lagan), two Nationalist (Derry and Fermanagh/Tyrone) and two marginals (Armagh/UB and Belfast).
A bit rough Andrew but if you take the 2011 election results, weight them by district population and add them to approximate to your proposed regions you get what you predict but the interesting thing (for me) is no party has overall control and a UUP/SDLP/Alliance shared future tie-up (a different UUP and a different time maybe) has between 37% and 43% in five of the areas, and 32% in Fermanagh/Tyrone. Some potential for a future ‘shared future’ coalition if the GFA wing could win back the UUP.