Very sensible advice. Some rail passes are best bought outside the country/area. That is because they give preferential rates to tourists and they are bought through the official tourist/rail office but do check. You then have to validate the ticket at a railway station on the first day of usage and allow a few minutes for this. usually it is at the advance booking desk NOT at the barrier.
Some of them allow you to use it on ANY ten days in the month. Others are FOR ten days in the month STARTING with the first day of usage, just check.
Another advantage of trains when travelling with small people, they can wander around more and so be less bored. A disadvantage of trains when travelling with small people, they can wander around more ...