as I think was said earlier, the Road King is the most elemental of the serious long distance touring bikes, no extraneous bullshit to get in the way, just a rock solid steam ship of a bike that loves nothing more than to sail across the western plains for hours on end at 85 MPH. The nice thing is is that in the states at least you can rent one fairly easily and take it on a little 500 miles spin to see if it's really for you. If it is, you'll find it's perhaps on of the easiest bike there is to dial into your particular needs. Cruise, racks, seats, shields whatever, if you need something a bit different than stock, odds are there will be any number of alternatives available. I use a sport touring bike now for long distance travel but I must admit, even tho I'm more a 'Stich than fringe leather kind of guy, I still miss the King.
“many a trip continues long after movement in time and space have ceased”- Steinbeck