Maldives like James said mate ,thats if you can afford it. Its not a backpackers place though unless you are a bum surfer and spend the whole time on a surf charter.

Be 10 g plus for 3 weeks easy in a resort there, absolute luxury though.

Fiji, Tonga, Vanuatu. In order from the most touristy to the least.
Safe in regards to terrorism, kidnap or disease, but like anywhere you can be had in tourist shops and come out with what you didnt buy. Goods not as cheap as Asia though.There is an island Where only couple go on Fiji no kids allowed! Its a paradise and its very affordable. You can walk off the little island resort and go around other places from there each day or stay put.

Vietnam Cambodia Bali would be the go for shopping and cheap travel but you have to watch your asses if you go off the beaten track in Cambodia. Bali's monkeys and some dogs have rabies, imagine you'd need malaria tabs for some areas too.

Southern Thailand is much more open and more friendly/country style than the bustling Center, then you can cross the boarder into Malasyia to Penang and one night in a boat gets you to Medan the capital of Sumatra.

Papua New Guinea is cheap and less geared to tourism but amazing if you want a more raw adventure in untouched paradise, guided would be the go here. Malaria tabs again.

Careful in the trains and public transport in India, do your research,borrow A travelers guide to India from the library. Note which buses to avoid (as some get worked by pros) and dont except lollies off old ladies on them either or you'll be off to sleep and robbed in no time.