In my experience, American models can sometimes be a little tricky to sell.
The "Model Power / Lifelike / AHM" brands usually tend to fetch little money on ebay when sold individually.
The Bachmann American models often do sell reasonably well.
A model shop that sells secondhand items might consider some of these items may be on the shelf for quite a while before a potential buyer turns up.
If you live near an auction, such as the twice yearly train sales that Andrew Hartley, in Ilkley, for example, it may be better to ask for an opinion with a view to splitting the locomotives and wagons into joblots.
There's various options, maybe a stall at a local toyfair - these usually cost around £30 for a day and the other traders and dealers may be willing to take the remaining items at close of play. Good luck and all the best anyways, whatever you decide to do. There's obviously sentimental value to them, which money can't buy !