Gelsenkirchen - 30 June

Hotels:

Ibis Styles
Located directly opposite the main station and thus also a stone's throw from the FlixBus coach station. Soundproofed, no-frills rooms. Free Wi-Ffi. Breakfast buffet. Approx. 26 minutes to the ground by tram. 

Good morning Gelsenkirchen
Also right outside the main station. Free Wi-Fi. Bar and breakfast buffet. As for the Ibis Styles, c. 26 minutes by tram to the ground.

Hotel La Scala
Away from the city centre, in the district of Buer, this hotel has its own restaurant and bar, and, if you're driving, free parking.

Hostels:

The Bunk Hostel
Located down the road in Essen, but right by the main station (and thus also the FlixBus coach stop), so you can be at Gelsenkirchen main station by train in just 13 minutes. New, modern hostel. Rated 'Fabulous' on Hostelworld. Free Wi-Fi.

a&o Dortmund Hauptbahnhof
Also out of town. This time in Dortmund. Budget hotel rooms and beds in dorms on offer. Situated less than 200m from Dortmund main entrance to the main station, with trains to Gelsenkirchen that take under 30 minutes. 24-hour reception. Free Wi-Fi.

Holiday homes:

Large apartment with garden
Located in a suburb of Bochum, but less than 25 minutes by car from the Arena AufSchalke in Gelsenkirchen). Well appointed, large apartment with garden. Quiet location. Sleeps 5. Terrace.

Apartment in central Gelsenkirchen
25 minutes on the bus to the Arena AufSchalke and 10 minutes to the main station. Modern, as new apartment with three bedrooms. Sleeps 5. 

Holiday home with charm and comfort
A fully furnished villa, just a 10-minute drive from the Arena AufSchalke. Sleeps 9. With pool and hot tub in the garden. Owner lives next door and is on hand to provide any necessary assistance.

Campsites:

Campingplatz Tögemannsfeld
750m walk to OER-E. Jugendherberge bus stop, then bus and regional train via OER-E. Mitte and Recklinghausen Hbf to Gelsenkirchen Hbf. Total journey time: 55 minutes. See Deutsche Bahn website for train times and tickets.

Knaus Campingpark Essen-Werden
700m walk to Essen Werden bus stop, a 5-minute bus ride to Essen Bredeney, then 12 minutes on a tram to Essen Hauptbahnhof, followed by 8 minutes on a regional train to Gelsenkirchen Hbf. Total journey time: 46 minutes. See Deutsche Bahn website for train times and tickets.

Other nearby towns:

For relatively easy train connections (once you've made it back to the train station) the following towns are options for accommodation:

Essen

Bochum

Dortmund

Düsseldorf

Oberhausen

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

For the first 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.