Not sure if this is a bit too sporty for what you are after, but my Triumph Sprint ST is the best mile eater I have ever owned.
It has high clip ons, panniers as standard and I have fitted the aftermarket gel comfort seat. Tank range is about 200 miles and it is so comfortable- and the great thing is that you can have great fun in the twisties too. The triple motor is full of grunt and character too- sounds great with the TOR end can and the fuelling is perfect.
A bike you can tour on without feeling like a pensioner! In the UK much chepaer than Beemers and Guzzis too.