I propose to shake up this pattern by adding tradeable equity instruments (and possibly also debt instruments).

The equity instruments work like this: if [po] owns the Old Kent Road (U.S. - Mediterranean Avenue) and [dub] owns Whitechapel Road (U.S. - Baltic Avenue), instead of glowering at each other un-co-operatively, they can float a joint stock company. The company can own the properties and, because it owns the full set, it can build on them. [po] and [dub] relinquish title to the properties and, instead, hold shares (equity) in the company.

To protect the interests of minority shareholders, the company is only allowed to take certain, clearly defined 'corporate actions', some of which require unanimous consent of shareholders, others, a simple majority. These actions would include raising capital from shareholders (to build houses, presumably), selling additional shares into the open market (also to build houses, presumably) and distributing cash to shareholders (as a dividend). Certain 'Chance' and 'Community Chest' events (notably 'repairs') might be interpreted as affecting the properties of companies in which a given player has a shareholding, much to the annoyance of their fellow shareholders - who may, if they decline to provide the necessary extra funds, trigger the bankruptcy of a company.

For the real lover of gratuitous complexity, we can then allow these companies to issue debt securities (corporate bonds). The issuing company must pay a fixed amount to the holding players every so many turns (so, someone must be keeping careful count of turns), and/or must redeem them for their face value at the end of a somewhat longer period.

The main objection to all this is the extra paper-work. One way to overcome this objection would be to play this game only in an on-line format, where the book-keeping could all be computerized. Another would be to supply plenty of pre-printed cards and papers for share certificates and company records and, maybe, to have the banker act as a full time 'central banker-cum-regulator-cum-registrar', and not participate competitively in the game at all.

The main effects of all this (apart from sorting out the Gordon Geckos from the Arthur Daleys) would be
1. to get houses and hotels on the board faster.
2. to reduce the impact of on-board events on players' ability to make deals.

Effect 1 might shorten the game (in terms of number of turns, though maybe not elapsed time), because the big, bankrupting liabilities (landing on hotels) could start happening sooner.

Effect 2 might lengthen the game, because a rapid conclusion to Monopoly generally relies on the emergence of brutal inequalities, and my proposed rule changes, enabling better risk-management, might delay the emergence of those.