I think it breaks down this way:

DIY Leisure Opportunists: People who frequently take leisure travel enough to know how to book their own reservations, etc. Typically skipping the travel agency, choosing from a preferred set of airlines. Service is slightly more important than price.

Just-For-Fun Leisure Travellers: These people rarely take airline vacations and will book on the 'spur of the moment' (3 months or less advance) and are not as concerned about price. these people typically book via a travel agency and rarely have any interest in frequent flyer programs. Service is equally important as price.

Price-Driven Occasionalists: These people take about 1-3 trips a year. they won't be terribly interested in frequent flyer programs, but you can bet they still have a card for most airlines, even though they will typically not have status on any carrier. These people are extremely price concious and frequently book from sites like Priceline.com or HotWire. Service is less important than price.