Central aparthotels
Adagio Luxembourg City in Kirchberg is the biggest and most reliable — full kitchenettes with induction hobs, dishwasher, oven, from about $140 for a studio. There's an Auchan supermarket 3 minutes' walk away. Citadines is not yet open in Luxembourg but Staycity in Gare has similar setups at $130-$170 with a Cactus supermarket next door.
Longer-stay picks
For a week-plus, look at LuxairTours' serviced flats in Belair or the aparthotels around Place de Paris — weekly rates drop to about $100-$120 a night. Hotel Simoncini has a couple of kitchenette rooms in Ville Haute but they’re small and pricey ($200+). Real advantage of a kitchenette in Luxembourg: breakfast. Hotel breakfasts here run $22-$30 — a supermarket run is $5.
Good to know
Are supermarkets easy to reach?+
Yes. Cactus, Auchan and Delhaize are everywhere, and central branches open until 8pm weekdays, 6pm Saturdays. Almost nothing opens Sunday except gas stations and the Cactus at the train station.
What about Airbnb vs aparthotels?+
Airbnb is legal but limited and often not much cheaper than aparthotels once cleaning fees are added. For 3+ nights, aparthotels usually win on price and flexibility.