I am struggling with the same issue, but my 2002 SUV has just under 200K on it. I about decided to keep its til it dies. I've only replaced the power steering pump so it has been extremely reliable.
Was thinking I could get more out of it if I traded before it dies, but the age and mileage make it not worth much running or not.
Plus one of my buds has a 2004 Tahoe with 295K on it and he drives it every day.