I seemed to play this differently to everyone else - and indeed probably to the way the game was designed, in that once I was installed as a chairman in a company I stayed there and just bought out any others that I needed in order to make the connection between the major cities that is needed.
I don't remember the name of all the companies, but I started in the top corner of the map, gaining access to one of the cities there. After upgrading everything, a bit of re-routing, and, especially placing hotels in all cities - especially the city hub itself as those generated up to $175K, or more, every year.
I then went hunting for another railroad to take over. This got me into another hub, where I repeated the process above. This time though I could also expand the exisiting railroad to a near by city to bring in extra money especially as I could buy some industries along the way (this money is channelled back to the player in dividends naturally.)
This was then repeated a third time with another 'cheep' company, but making sure that everything was linking up along the way. This would usual mean deleting the hub station of the company I'd just bought and, instead, re-routing the tracks into another companies station. The one I intended to buy next, of course.
New York was the hardest one to get into via this method, and one I probably should have done earlier as you get two points for that instead of one for all the others. but it was done eventually although i hadn't budget for the manhatton access costs, which delayed that a bit, as did having to knock down a few buildings in order to build the access bridge - eventually bridges - where I wanted it/them.
I did buy a better engine - the Zephyr - but only later on, when money for my company wasn't an issue and I needed to out service another company so I could crash it's stock price, in order to buy it out. I didn't buy anything else, although i do like the way that was set up.
Anyway, managed a silver when the time was up, with a rather frustrating, 98 points, just two short of the gold..
Still this was great fun to play, especially as it forced me to play in a way I usually don't - I'm more of a builder than stock trader - so great respect to the map builder