I really disagree with your reasoning for the increased probability to land on railroad spaces; the expected number of times that a player will land on a railroad space per trip around the board is only 33% more than the expected number of times that a player will land on an orange/red/yellow space per trip around the board, and that's only because there are 4 railroad spaces to 3 of each colored space, not because they are more "evenly distributed." Furthermore, the convenient locations of the orange, red, and yellow properties relative to the Jail and Go to Jail spaces more than offset the added likelihood of landing on railroad spaces via Chance cards, not to mention that there are a couple of Chance cards that favor those spaces anyway (Go to Illinois Ave., Go Back 3 Spaces, and Go to Jail).
Fact: the most common spaces to end up on are Jail, Illinois Ave, Go, New York Ave, B&O Railroad, Reading Railroad, Tennessee Ave, and Pennsylvania Railroad, in that order. The railroads are the 5th, 6th, 8th, and 25th most landed on spaces on the board. (1)
The reason that certain properties have different probabilities of getting landed on is because of chance cards and 3-double rolls ending you up in jail. You'll notice that Boardwalk is the 18th most landed on property, while Park Place is the 33rd.
The reason railroads work is the fast pickup, quick return, and high ROI. (2)
Of course, in a game of Monopoly with professional players, what strategy you go for will typically depend on what properties you are able to purchase. You luck into the orange monopoly in the first 5 passes? Well you've probably won. Think of the railroads as a rush strategy (where possible), and combinations of streets being the more commonplace ones.
(1)
http://www.tkcs-collins.com/truman/monopoly/monopoly.shtml(2)
http://www.amnesta.net/other/monopoly/
