I went 2 years ago, spent 2 weeks in Seminyak in the honeymoon suite at an amazing small (10 rooms) boutique hotel
http://www.baligingersuites.com/ the service was incredible and the price was very reasonable. (<100/night) It was quite central and a 5 min walk to the beach.
As others have mentioned, be prepared to haggle while shopping and be pestered on the beach by people trying to sell you stuff(including sad-faced children). I'd recommend renting a chair on the beach from a local (i'm not convinced they own the loungers but they will clean them and serve you drinks from the restaurants
I also spent a week in Ubud at a majestic, albeit, ridiculously expensive resort owned by the royal family
http://www.royalpitamaha-bali.com/ with an absurd amount of stars to walk, great after skipping 3 weeks of workouts!
Ubud is a very laid back, hippie like place. Very relaxing.
Wherever you stay, hire a driver for a day or 2. Its is very reasonably priced ($50/8hrs) and the driver will (should) know places that you will want to see, excellent restaurants (don't forget to offer to have him join and mention that you will pick up the tab, they are very grateful) as well as help you barter at shops.
Feel free to ask questions.
Also, don't forget to try to poop coffee...
https://en.wikipedia.org/wiki/Kopi_Luwak
On second thought, after reading the wiki page, maybe avoid the poop coffee...