Wulai is a nice day or weekend trip out of Taipei. Full Moon Spa is a great choice. The room we had had a big wooden hot bath in the room, everything was in camphor wood, the bed was very nice, had a large flat screen tv. Its listed price was nt$6000 a night, but even on a holiday they quoted us nt$4500 a night even without us asking for a discount. Very clean, very friendly. Includes basic breakfast and dinner, dinner is a standard Taiwanese tea house biendang, not bad. Breakfast was very simple, western or chinese. The communal hot spring was spacious and uncrowded.
Going to Wulai is great if you're going for the soak, but there is very very little to do unless you want to walk up steep trails.