More Retirees Discover Small-Town South
American retirees who once flocked to Florida, South Carolina or North Carolina are migrating in steady stream to rural South; they are being lured by temperate weather, inexpensive living and savvy marketing by community leaders who have learned to court senior citizens aggressively; retirement has become growth industry with the aging of baby boomers; business and political leaders in South see vast potential for economic development in retirees, particularly well-heeled ones; they bring bank deposits and buy houses, food and clothing; they pay taxes, place little strain on most municipal services, do not pollute, rarely commit crimes and often volunteer in schools and hospitals; Florida's share of retiree market is still largest, but many migrants to other Southern states are moving from Florida to small towns and cities of Mississippi, Alabama, Georgia and Arkansas to escape crowds, crime and traffic; photo; map (M)