Europe is too cold this time of year, so is Japan.
I did a 10 day solo vacation to Bali, Indonesia in 1997. Had a great time. Went mountain biking in the rice fields; hiked up the tallest mountain ( volcano ) on the island; SCUBA dived on a sunken WW II wreck off the northeast coast; lazed on the beach; took in the cultural shows at night in Ubud. Cost all of $350 for ten days ( excluding air fare ).
Avoid Kuta, bunch of drunk Aussies there. Spent one night there and then headed up to Ubud. Had my own villa in the rice patties with breakfast served on the porch in the morning. Cost me $9.50/night. Spent another a few days at a beach motel in Sanur.
Typhoonpilot