Mark - One idea I've always found intriguing for this kind of problem is to use what Iain Rice, in his book "Small, Smart and Practical Track Plans", calls a cassette. You'd have to see his book for details on the construction, but it is basically a train-length of straight track that you can connect /disconnect to your layout or staging area. Run a train onto it from your layout and then move it (and the train) to your staging area and run the train onto the staging area, or vice versa. The staging area can be hidden, located across the room, or whatever.