Collecting little countries and got as far as the "L"s?
If you are in Zurich I would suggest visiting locally - certainly Luzern and the area around with Pilatus and especially Rigi. Loads of hikes on Rigi. Plenty of extraordinary scenery on and around the Vierwaldstaettersee (Lake Lucerne in English) and maybe the most beautiful large lake you will see in many a day.
The town of Zug and its lake is no slouch either. How many towns have you seen with a lakeside promenade with snow covered mountains all around, with exotic birds in cages under the trees right on the waterfront - free to visit with no entry charge?
All areas of Switzerland have spectacular scenery to one degree or another, some more than others, and I give Vierwaldstaettersee and the Lauterbrunnen Valley mountain villages and area a full 10 out of 10, and Luzern 8 out of 10, I would give Liechtenstein 3 out of 10 if you have to pass through, 1 out of 10 if you have to make a special trip.
Luxembourg is a much larger country, with many many attractions, than it looks on the map. The city of Luxembourg City is very different from anywhere else in Europe with pastel coloured cinderella towers, caves and casemates, valleys and bridges crossing bridges, all on multiple levels connected by ramps, stairs, walking paths, and lifts/elevators and escalators.
The country itself is worthy of many a day. Each region is different to the others, everything from meandering riverside paths and bridges overlooked by beautiful vineyards, to agricultural areas, to the area of the major battles of the Battle of the Ardennes (Battle of the Bulge) with a world class volunteer run Battle of the Bulge museum at Diekirch. And the clifftop castles, oh my.
And General Patton's grave with those of his men just a few miles out of Luxembourg City.
And Trier is a very historic German city with Roman roots which is adjacent.
Points out of 10? For me, as I drive through it every year and always stop, maybe 7 or 8. But it is so blimmin far from Zurich. It really is a long way, either driving or even further by train. There is so much fabulous scenery and hiking, and boating, and beautiful towns and vineyards both sides of the Rhine, oh so very much. There are huge swathes of Germany and France before you get close to Luxembourg. Rhine ... Moselle ... Black Forest ... Alsace ... Heidelberg ... the list is huge.
So, my idea of going to Luxembourg as day trip? Almost impossible. As an overnight, worthy of a 1 or 2 unless you have exhausted everything in between. If you have a week, 7 or 8 or 9 depending on your preferences.
I hope you have a great trip.