Also when you start with populated cities they are generated with car parkings or theme parks and few other buildings, it wouldnt be bad do add them to city build interface, may be even add entire "decoration" section. They can even play some role in quality of life in city. I wouldnt mind to add even more in game, but for now why not use what is already in game.
Another thing, may be add posibilities to build docks and airports too, probably restrict airports to just one in city and give it some minor bonus to city exports
Also the stock market, central bank and information center, if nothing else builngs looks nice and are good even just as decorations, but they also can surve some other propose and even provide some minor jobs on the market.
Also seems a lot people strugle with rising city population due to the lack of jobs, i might be wrong but currently only player corporations and city functional buildings provide jobs in the market, but in real world there is truck drivers, delivery boys(and girls
), plummers, builders, barbers and much more. May be at end of the year when city population growth is calculated add/remove some jobs to the market based on population increase/decrease, for exaple city population increased by 30 000 for the past year, add 10 000 jobs to the pool, it decreased by 3 000, remove 1000 jobs of the pool. Its not perfect solution but its easest and simpliest to impliment i think. The exaple is for 1/3 ot population working "elsewhere", but you can use another ratio to be more balanced.And the last thing for now, may be put some "maintance" on parks, and make then provide some minor bonus to city enviroment for the quality of life, they can serve to conter the effects of polution to some degrees in cities with heavy industry.