Out of curiosity, how many turns do people (excluding the dev team who obviously has to restart a lot for testing) tend to play their campaigns? I find myself getting a little bored around the 200-300 marker, which is a significant investment of time.
My play style usually goes like this:

1) Play Rome, expand slowly and historically using a map of the Roman conquests and the calendar as rough guides.
2) Finish constructing tier 3 military colonies in the relevant cities in Italy and upgrade them to IusLat's
3) Eventually start to get bored with waiting for 500 to be able to get troops from provinces directly and play with those sweet, sweet legions for my Wish Fulfillment Vehicle.
4) Start over with a new update but edit it so you can hit the Marian reforms early, still start to get bored around 300 as it's much of the same improve provinces, take new ones, develop political careers of my leaders
5) Try a different faction. Read all the descriptions and love learning about their history / reform requirements etc / province descs
6) Get to 150-200 and get bored with not being able to develop roads and civic architecture as much, and not having the carrot dangling of sweet reform troops coming like the legions.
7) Try Hellenic faction because of their advanced architecture and two tiers of reform
8) Burn out fast because managing your Hellenic culture %'s and colony points is the same kind of spreadsheet play that I was just doing for 300 turns with Roman Cursus Honororum management (I LOVE the system and don't want to change it! But eventually it gets a little repetitive over every 4 turns shuffling some of your generals as I have people at all stages of the 5 year timer, over and over for hundreds of them).

So mostly in posting looking for two things:

1) Some sense of how long other people play their campaigns before they get bored and move to a fresh start to gauge where I'm at compared to them
2) Suggestions for factions that are interesting to play as far as having long term things you can work towards without being too repetitive, or having poor civic architecture or troop reform options such that you feel you've maxed out too quickly.

And definitely not intended as a criticism of anything.