I did 3,500miles round europe this summer (11 days riding). Most we did in a day was 500 miles. We found that the endurance of the bike was better than us - we needed to streach on average at about 100 miles.

Comfort - I thought the seat would be my biggest problem, but it was actualy my hips and arms that sufferd the most. However, the more miles you do, the easier they get 8)