Ngaire - My suggestions:
1. Do go to Ubud. Visit Agung Rai Museum of Art (ARMA) in Ubud Bali, which is located on Jl. Pengosekan in downtown Ubud. It features Indonesian painters along with dance and theater classes. We were there when they were teaching young girls the basics of Balinese dance. Seeing that class underway was among the most memorable parts of our visit.
2. If you have time, have lunch at Ku De Ta restaurant in Seminyak at Jalan Oberoi 9. Phone is 361/736969. Probably the best of the restaurants we visited & a lovely beach location. If not, Dirty Duck near Ubud seems to be a favorite choice.
3. Don't try to head up to the rice fields. Traffic takes forever.
Cheers, Anne