Hi Puddleduck,
Only returned from Burma / Thailand this weekend and have just seen your enquiry.
Do you intend to book a package or will it be DIY. If a package we usually take advantage of any early booking offers as Bali is busy at that eime of year (we have not tried August as it is UK school holidays and we avoid them like the plague).
If you are looking to take a package go for Sanur, for your first visit, - Nusa Dua is contrived and sterile, Kuta is a bit manic with loads of younger Aussies (it is their Spain), Seminyak is expensive and, to us, not really that appealing. As Fiona says, also take a couple of nights in Ubud for the temples, dances, crafts and above all the wonderful inexpensive spas and relaxation.
I have the name of the owner of a trusted local tour company, who has arranged several things for us plus numerous rooms / trips / meals for Janet (my wife's) company. He is one of the few people that I would not hesitate to recommend - his prices are low, he is honest and thoroughly reliable. If you do your own flights his hotel prices can be a lot cheaper than booking directly with hotels (recommend Hyatt club rooms or Puri Santrian - Hyatt mainly for location). His advice is also good!
Please pm me if you want his details. I have major PC problems at present and am very busy after our hol, but will try to get back to you as soon as I am able.
Cheers
Peter