Ge0rge:quickymart:
The Wairarapa train from Masterton to Wellington does well, you can take a day trip to either destination on that one, and I think (but could be wrong) the distance is similar.
Unless you want to ride a bus over the Remutaka Hill, there are only three morning trains into Wellington and three evening trains leaving. The two off peak services in either direction have been replaced by buses since January this year and, according to Metlink, will be buses "until further notice" - apparently it could be two years!
This must be a recent change, sadly I haven't been to Wellington a few years now.