Ofcourse there is more to see and do in the Müllerthal and Sauerthal area. For mountain bikers who are not here for only mountain biking and brought their family to Luxembourg there is enough to see and do. Here are a few tips and links:
There are also fixed mountainbike routes in the Müllerthal area. These are less technical and strenuous to ride but they are also not so breathtaking.
https://www.mullerthal.lu/en/discover/biking/mountain-bike
You can also rent an e-mountainbike if you want to discover the beauty of the Müllerthal but don't have a good stamina to climb all those trails.
https://www.mullerthal.lu/en/discover/biking/bike-rental
If you have technical problems with your own mountain bike or just interested in something new you can visit the following bike shops for advise.
Just across the border in Germany https://sattelfest-bikes.de/
Somewhat further away https://ostergaard.lu/
For one or more overnight stays I can only advise the following accommodations because I stayed there myself. It can be cheap at:
Bed & Breakfast Alferweiher (see Booking.com)
Trail-Inn Natur & Sporthotel Berdorf https://www.trailinn.lu/
Or very cheap at the Youth Hostels:
Restaurants:
One of the not so typical Luxembourgian restaurants in Echternach.
Aal Eechternoach https://aaleechternoach.lu/
A very good pizzeria where besides Italian also Portuguese and French cuisine is served.
Restaurant Pizzeria Lenert https://www.restaurant-lenert.lu/
Not only a hotel but also good for a good lunch or dinner.
Trail-Inn Natur & Sporthotel Berdorf https://www.trailinn.lu/
Bistro Martbush https://camping-martbusch.lu/en/facilities/restaurant/
Family trips:
A real Dinosaurpark just across the border in Irrel (Germany). https://www.dinopark-teufelsschlucht.de/
The beautiful castles of Beaufort with a nice hike along the Hallerbach stream.
https://www.mullerthal.lu/nl/fiche/castle/kasteel-beaufort
For an easy kayak adventure on the Sûre river.
https://www.mullerthal.lu/en/fiche/watersports/canoe-and-kayak-dillingen