Masterton is about 100 km north-east of Wellington — around 90 minutes by car over the Remutaka Hill on State Highway 2. The Metlink Wairarapa Line train runs five times each weekday and twice on weekends from Wellington Railway Station, taking about two hours and going through the Rimutaka Tunnel rather than over the hill.
The road is winding and slow if you're held up behind a truck. The train is more relaxed but the timetable is built for commuters, not day trippers — check connections carefully. From Masterton, most of the Wairarapa attractions need a car: Pukaha is half an hour north, Greytown and Martinborough are half an hour south, and Castlepoint a full hour east.