I was in Bali 3 summers ago (2008) and had an amazing month long trip starting in Ubud, traveling south to Seminyak, then up north through Munduk, Lovina and then east to Amed and back to Ubud. Along the way I stayed in many amazing hotels and saw incredibly beautiful sites. I will try to remember the highlights since a few people have recently asked me for tips.
Ubud is the cultural center of Bali and offers the best in art, food and local tradition. The town is quite small and most sites are reached by foot or bike, or cab. It was by far my favorite place in Bali and I returned there 3 times in the month that I traveled.
The best place we stayed was Honeymoon Guesthouses Ubud. The hotel was amazing, the location was perfect, pool, helpful staff and they offer very inexpensive spa services. The other place I stayed there was Ubud Terrace, which was less expensive and perfectly comfortable…and very close to Monkey Forest.
Next was Seminyak which is a beach town next to Kuta. There is a thriving nightlife that is way more European and Australian, and a few days here (and south to the surf beaches) is definitely worth your time. I still preferred other areas of Bali more for the authenticity, but a day on the beach watching world class surfers then heading to a good “foam party" never hurt anyone!