Only one hour per car is the famous basilica of Mariazell. A real pilgrimage of course if by foot, so if you have time you can try it too; otherwise it is very well reachable per car – through picturesque landscape.
There are many different ways to Mariazell. Drive/Go through Veitsch, that would be a perfect route if you want to combine your day trip with the Stations of the Cross in Mitterdorf and the Pilgrimage Cross in Veitsch.
Back home you can drive in direction Mürzzuschlag over the Lahnsattel and Mürzsteg. Its a very nice route.
The famous Basilica: Basilika.
Especially nice is the Advent Mariazeller Advent.
There is a bus (Postbus) from Mürzzuschlag to Mariazell.
Once in Mariazell you could take the rack railway to the Aflenzer Bürgeralm. From there you have a great view, can ski in the winter and there is an outdoorpark for the whole family. Outdoorpark.