Ibiza
The party capital of the world, Ibiza is the ever-popular Balearic gem that attracts millions of visitors every year. September is as good a time as ever to absorb the islands beauty and vibes, with the parties of San Antonio and Playa D'en Bossa carrying on to the end of the month and into October, when the closing parties occur and the island's pleasure-and-party-seekers say goodbye to another successful season. Aside from the parties, Ibiza has a very grown-up, luxury side to it that is enjoyed by families and couples alike, and is relatively untouched compared to it's hedonistic neighbours. Weather is still warm is September, but prices drop, as does the hustle and bustle.
Tenerife
It's hard to say which month is the best to visit Tenerife, with it's sunny-to-moderate year round climate and tourist-friendly, holiday-ready resorts, but September is definitely be up there. Another Spanish island that is popular with anyone from party-goers to families, Tenerife is the largest of the Canary Islands, and a result of the eruptions of Mount Teide spanning some 100,000 years. Mount Teide still dominates the islands skyline, and is a popular tourist destination, along with the resorts of Playa de Las Americas, Los Gigantes, Los Cristianos and Los Gigantes. However, the north-side of the island is a haven of natural beauty and deserves some kudos too; with it's national park, incredible hikes, rugged coast and untouched beaches.