Bali is nice, however if you have enough time I would suggest to combine Bali with a few days on one of the small islands off Lombok (the neighbouring island, some 20 minutes by air away).
Bali is rather touristy island, with Nusa Dua among the most developed parts. Bali is great to explore by car, plenty of sights etc. But - if you want something less developed, less crowded and more laid-back, you should consider splitting your time.
Last year, we spent a week on Bali and another on Gilli Air, off Lombok, an island without much in terms of roads or cars. Great swimming / snorkeling / diving, too.
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