I think Spitzer was on to something; we don't need to reinvent the game, just add another layer (or two) of addenda in which everyone can be a banker, a property holder or both. Side bets would be encouraged and regulated, and the rules governing the game occasionally altered by chance (or election) cards--along with the potential to mitigate results of such a card by paying a fee (buying the election--"Supreme Court ruling in your favor, your corporation is now a legal person and you may determine the outcome of all future elections").

An official variation that my family finds quite addictive is the card-based version, Monopoly Deal.

Also, I'd like to play a version in which the players stay connected via smartphone and actually have to travel through the streets of Atlantic City in order to play.

There are so many special editions of Monopoly out there (as an au pair in the UK I had a hard time convincing my employer that the London Monopoly was not the original) that talk of redesigning or maintaining the game is almost superfluous. The rules are the only thing that haven't been formally altered that much and many families have their variations such that the original rules are nearly as insubstantial as the setting.
I have a soft spot for the history and circumstances evident in Monopoly as played with its original setting and always prefer the Atlantic City version.

Stefan