Stalkers. Groupies. Either way, this is a big summer for aficionados of long, languid sailings on the Mississippi River and beyond. After a four-year absence of multi-day leisure cruises, the American Queen, a 436-passenger boat built in 1995, is back on the river.

In August, the new 150-passenger Queen of the Mississippi will enter these newly competitive waters. That boat will have lower density, larger cabins (most with private balconies), and, at an average $640 a day per person, a steeper price point.

Not that the American Queen, with average per diems of $500 per person, ranks as a budget vacation.