Düsseldorf

Hotels:

Ibis Düsseldorf Hauptbahnhof 
Stayed here for a Union game a couple of years ago. You know what you’re getting with an Ibis hotel, and this one couldn’t be handier if you’re travelling by train or coach, as it’s built into the main station and thus next door to the FlixBus coach station..

Best Western Ambassador Hotel
Only 200 metres from the main station. 24-hour reception. Not a hotel I've stayed at myself, but almost as handy for trains in and out of town as the Ibis above.

Tulip Inn Hotel Düsseldorf Arena
The closest hotel to any Euro 2024 stadium?! This one is integrated into the Merkur Spiel-Arena, so couldn't be any closer. Breakfast room overlooks the pitch. 24-hour front desk. Free Wi-Fi. 15 minutes on the underground into the city centre.

Hostels:

Backpackers Düsseldorf
An inexpensive hostel for those doing the Euros backpacker-style. A 15-minute walk from the bars of the old town.

a&o Düsseldorf Hauptbahnhof
A 14-minutes walk from the main station (and thus also from the adjacent FlixBus coach station). Opened in 2009, the hostel offers modern rooms in a range of categories, plus a large lobby and bar.

City Youth Hostel Düsseldorf
Located on the far side of the Rhine from the city centre. 18 minutes by public transport or a 30-minute walk to the old town.From single rooms to dormitories.

Holiday homes:

Holiday apartment in Neuss
Two-bedroom apartment with modern furniture, located in Neuss, less than 20 minutes by car from both Düsseldorf city centre and the Merkur Spiel-Arena. Sleeps 4. A 3-minute walk to the nearest underground station, from where it's a direct 20-minute ride to Düsseldorf main station.

Modern apartment in Grevenbroich
Suitable as a base for both Düsseldorf and Cologne, as it's 24 minutes by car to Düsseldorf city centre and 33 to Cologne. Sleeps 4. Modern design and furnishings. Rated 'Exceptional' by 35 reviewers at time of writing.

Dorm-style accommodation in Kaarst
Sleeps up to 15. Can be hired in its entirety or partially. Facilities shared by all house guests. A 20-minute drive to the stadium.

Campsites:

Camping Düsseldorf-Lörick
1500m walk to D-Lörick underground station, then 16 minutes on the underground to Düsseldorf main station.

Camping Zweckverband Unterbacher See
850m walk to D-Stammesberg bus stop, then a 7-minute bus ride to Düsseldorf-Gerresheim and 5 minutes on the S-Bahn (metro) to Düsseldorf main station.

Other nearby towns:

For relatively easy train connections the following towns are options for accommodation:

Cologne

Bonn

Wuppertal

Essen

Bochum

Dortmund

Oberhausen

I've a full page on Cologne and on Dortmund here and here.

For the first group-stage game, I stayed one night at the Best Western Ambassador Hotel in Düsseldorf and post-match at the NH Hotel in Oberhausen. Both were within a 5-minute walk of the respective stations. For the Cologne and Round of 16 game, I stayed various nights at Hotel Löhndorf and Hotel Mercedes City in Bonn and Hotel Domspitzen in Cologne, all also close to the respective stations.