If you truly want to give the game another chance, then learn from your experience, and adapt your play accordingly. Specifically, you are not punished for succeeding in war, but there are consequences to growing too much without sufficient happiness. It makes no difference whether the growth comes organically, or from conquest. If you don't have sufficient happiness to absorb the population, you have to pay the price. How you choose to deal with this is up to you.
Well, i'm ok with a penalty for outgrowing, but, honestly, i'm not a fan of how it's currently implemented:
-by outgrowing, i'm lacking happiness. My goal is to get happiness
-being far in the unhappiness treshold, i have no growth, fewer production and combat maluses + rebels appearing...
-what are my solutions?
I know people don't like comparison to Civ4, but honestly, that's the only thing i can make.
In Civ4, overexpanding means generally to lower the science rate to support the cities during the time i need to grow them up
In CivV, i need to have new buildings that i can't build (because it's already so long and now i have a penalty + i have no growth so i can't work anymore tile), i need to fight against rebels with a -33% malus, the best thing to do is put all cities on gold focus, connect cities to trade route asap and buy colosseum and courthouse...
Bite me if you want, but it's becoming "buy an empire to stand the test of time"
Thinking about it, the penalty for unhappiness shouldn't be on cities but on the whole empire (like happiness is managed): In civ4, you were adjusting the sliders, so overexpanding had effect on the whole empire, not in all your cities. In Civ5, the growth and production malus is on the cities. You should give instead a penalty on the science or gold output of your empire. from -1 to -10, you need to pay some gold, from -10 to -20, you have malus on science (-X%) and from -21 and under, you can start having rebels, but without any malus on combat against them. Of course, numbers should be worked, but i think it will be felt less painfull than the way it is now...
About the 5 points of Sullla, well, i don't play MP, but if it is non-existant because of really severe issue, well sure it is really problematic...
-Diplomacy: well, there are still some criteria that we don't see that determine friendship, because, how can Bismarck been enthousiast when there are only red criteria on screen? Plus, we need more way to get the AI friendly (make them value positively trading, give more trading options, add a trade route exchange after right of passage), get rid of possibly abusing trade like gold VS gold per turn, and a serious revamp of denounciation. I will make a chart, but on my current game, i think all 8 remaining AI have all denounced each others...How do you get rid of a denounciation in friendship determination?
-Player being punished: it's true i'm not a fan of buildings and road maintenance (especially road and railroad). The goal was to prevent people from building all buildings in all cities. Well, now people build the same buildings in all cities, but not all of them. Since gold is so much more efficient than production, i'm starting to think that i should just put cities on gold focus and sell all production buildings...It's not rewarding to build windmill and workshop just to have the city focusing on gold, honestly. I already explain my point on war reward...
-Global happiness: well, see my point upthere. It's not a bad idea. It's a bad implementation...
-1UPT: well, it can work with the following: better AI, easier movement and authorized stacking for some units with other civ units (especially workers).
I really think part of the AI problem is the fact they can't move well their units (blocking path of each other, etc...) and human boredom comes from that. The AI can't outflank you, they block their own unit easily because of limited movement. Removing the road penalty (and decreasing the trade route income) means road spam all the way, but it will be much more easier to move units and making war even more interesting than it already is. If this make the AI smarter, then it's a good thing... Maybe railroads can keep their maintenance cost, numbers should be worked.
Plus, workers should be able to stack over others civs unit, because i'm fed up of others civ units (especially City states ones) preventing my workers to make improvement and roads, notably in my own territory...