Here is suggestions for accommodation for each city. Please contact the hotels directly for booking.
OSLO:
Scandic Oslo City
Address: Europarådets Plass 1
https://www.scandichotels.no/hotell/norge/oslo/scandic-oslo-city
LILLEHAMMER:
Mølla Hotel
Address: Elvegata 12
TRONDHEIM:
Comfort Hotel Trondheim
Address: Krambugata 3
https://www.nordicchoicehotels.no/hotell/norge/trondheim/comfort-hotel-trondheim
DRAMMEN:
Clarion Collection Hotel Tollboden
Address: Tollbugata 43
https://www.nordicchoicehotels.no/hotell/norge/drammen/clarion-collection-hotel-tollboden/