Beinn Dorain is a good one as it starts straight from the train station at Bridge of Orchy. With both these hills by train though, there's quite a big gap between the trains. For Beinn Dorain, it's about 8hrs between the trains, so you would as well bag the other Munro - Beinn an Dothaidh. A fairly easy walk I remember, you've got the Bridge of Orchy Hotel there as well.
If going by train, from Glasgow Queen St. it's 2hr 25 to Bridge of Orchy and 3hr to Corrour.