I have been to Bali Twice. I even have made a simple site for a homestay i stayed in Lovina for only 5 dollar a nigh (now it is 15). That was the cheapest, but best most interesting place i stayed.
http://no.nl/4Hd Don't go to Bali and stay in one place. There are cheap and good homestay everywhere. For 25-50 dollar you have your own bungalow. if you stay in sanur a taxi can bring you to Kuta in 20 minutes.
I suggest to do: Kuta, Lovina, Ubud, Sanur. Than take the speedboat to the Gili Islands and go scuba diving. White beaches, clear water, bars, good hotels. It is more luxurious know then 10 years ago, but also fun. Than take a tour Lombok (Gili Islands are 10 minutes from Lombok). There was not much to do when i was there cuase of the bombing.
Malaysia is also great to go to. You can go to Borneo or the beaches at the mainland. Also a beutifull country. You can also go to Bangkok and travel to Malaysia and leave from Kuala Lumpur (done that also), than you can see Penang / lankawi. Or go to Cambodia for a few days, flying is cheap in asia.
I mostly take a look at the ticket prices. 2 years ago flights to Malaysia hit the bottom, so we went there. I don't mind in what order i visit those countries, as long i can see them all it is ok.
But wherever you go, if you just want to stay at the beach you can also go to the Bahamas or Mexico. If you fly to Kualu Lumpur, Thailand, vietnam you can always make a stop over in Hong Kong, Bangkok or Kuala Lumpur for a few days. Book your tickets online and choose your route.
ps, the sate on the street is the best!