Add another set of 3 cards that you get to keep once you acquire them by landing on these places (newly added spaces).

Card #1: Hire a skilled Accountant (least expensive card)
If you possess this card, you pay 0 taxes when you land on taxes-due.

Card #2: Hire a Lawyer (moderately expensive card)
If you possess this card, you can build Hotels right-away without needing to wait for even development). Additionally, you pay only half the amount than regular because your lawyer would help you establish the fact that your construction is for low income people and thus it should get federal/state help.

Card #3: Hire a Politician (most expensive card)
If you possess this card, you can declare any one of your competitor's property illegal and he/her would have to give away that property back to the bank. It will help you by breaking your competitor’s color-group (if any) which will automatically make his/her constructions illegal as well. You get this control when you throw a particular combination of dice, in addition to having this card. (the special combination of dice 6-6 is equivalent to your politician winning the election).

I like pretty much everything about it except the fact that going to jail becomes desirable at the end of the game to avoid paying rent to others. If there is no property left to buy, going to jaail should be restricted to no extended stay. This way, even if you go to jail, you do not stay there. You rather pay the fine and come out right away (or if you get double, your fine is waived).
Railroads can be removed for obvious reasons.

Rajeev