Hi! Must say I'm very happy to see someone else having the same experience as me with regards to pacing. Looking forward to trying this.
I have my own list of "wanted fixes", and thought I'd include a few of those mentioned here. I will not include balance issues, as these are already discussed here (and are going the right way). Note also that these are ideas only, not necessarily good ones. People might disagree based on expectancy and preferences, so I'll state that my best civ experience to date is Civ 4 with AND 2.x (which means hundreds of units in the empire (though that is not transerrable to post civ 5) and almost as many buildings per city), so this does cloud my judgement a bit.
- exponential growth of both production cost and production yield - meaning x% production increase buildings back. Would encourage building basic buildings first, which I kind of like. American colonies built a minor workshop, a saloon, some shops, etc before going all the way to factory. Make it so that early buildings help too much making later ones to be ignored in late cities).
- more building per district, yet with lower cost (about same total cost is current working theory). To accompany this.. each building has a lesser impact. Of these buildings few are prereqs to eachother, so there is a choice between buildings IN districts, not just BETWEEN districts.
- minor stacks (like armies, just capabable of holding different unit types, so you could "escort and archer". size upgradable by era, and never to stack of death/doom size. Maybe max 10 or something).
And on a different note. I realize this is very early in the game's lifecycle, but I see here in this thread many people with good ideas working on their own mod separately. Why not pull forces? Make a development plan and spread the work around (and in time work in a config tool for people with different tastes in how much to slow down / speed up stuff? Would need a quite dedicated group of 4-5 plus some testers i guess, so might not be there yet.