Where to go first week in October?

Currently living in Australia near perth and looking at taking a week off in October for our birthdays, can anyone recommend a memorable place to visit for a week? We were thinking of Vanuatu or somewhere similar. Where's best to go weather wise? We want nice beaches etc where we can chill out but also like exploring etc..
Any suggestions are welcome please! :)

Aitutaki for pretty scenery and a little exploring... beautiful lagoon

Ha'apai Tonga for swimming with the whales, (early October) memorable adventure

Looks stunning! Just wish it was closer! Don't really want a 24hr+ plane ride if only going for a week...

Vanuatu is a great choice - my personal favourite in the region!