In the city
Melia Luxembourg wins for families — connecting rooms, a pool, and Kirchberg's parks and the Philharmonie are a 10-minute walk. Family rooms sleep four from about $220. Novotel Kirchberg lets kids under 16 stay free in parents' room and has a proper play corner. Doubletree by Hilton in Dommeldange has a bigger pool than most and sits next to a forested park with playgrounds.
Outside the capital
Parc Hotel Alvisse on the north edge has an outdoor pool in summer, tennis courts, and free parking for around $150 a family room. In Mondorf-les-Bains, Domaine Thermal has thermal pools with dedicated family hours (10am-2pm) and a kids' pool. For a treat, Hotel Théâtre in Vianden gives you the castle 5 minutes uphill and a river beach for summer swimming.
Good to know
Do Luxembourg hotels offer cribs and extra beds?+
Almost always yes, and usually free for cribs, $15-$25 for a rollaway. Request at booking — supply is limited especially on weekends.
Any hotels with kids' clubs?+
Not really — Luxembourg is too small for resort-style kids' clubs. Domaine Thermal in Mondorf is the closest thing, with supervised activities during school holidays.