Of all countries in South America, Ecuador has the longest low season, lasting for six months from December to June. In Southeast Asia, Indonesia is the winner, with a remarkably long low season lasting from October through May. Interestingly, Norway and Finland each have a seven month-long low season, while the low season for the country in between them -- Sweden -- lasts only four months.
As for high season standouts, mainland Europe has two: Czech Republic and Switzerland, both of which boast a six-month period of peak travel. Similarly, Bolivia has the longest high season in South America, running May through October. The United States is fairly average, with a three month high season (June through August), a five month low season (November through March), and a four month cusp period (April, May, September, and October).