There is a UK company 'Steam Dreams' that specialises in holidays by stream train. I am looking seriously at:

THE GREAT LAKES EXPLORER – FALL 2020
Travel across the USA behind the World’s biggest coal fired
Locomotive - Milwaukee 261

But at the moment am booked on one in September this year round the Irish Republic drawn by much smaller beasts:

Throughout our time in Ireland we will be using the locomotives and coaches of the Railway Preservation Society of Ireland (RPSI). The set of 64 seat Craven Coaches are different to those used on our trains in the UK with more basic seating and décor but also a very singular Irish ambience with the only Bar Car in the world with draught Guinness. The RPSI owns a number of steam locomotives and it is planned to use No 85 Merlin and No 4 Tank Engine but others may be
substituted if for any reason these become unavailable.