I don't know how much luggage they have, but the advantage of staying near the airport is that they won't have to take it on a train, and then lug it to whereever they are staying.

From there, they can shuttle back to the airport and travel into town for sightseeing.

The Airport Crowne Plaza has rooms (advance purchase) as low as 92 Euros that night or 109 otherwise. A bit more with Breakfast. I haven't stayed there, but their web site shows a train station .5 kilometer away, might be within walking distance.