Best place (and only place) where to stay over night is Hotel Niskakoski some 500 metres from city center towards Juankoski canal and big factories that lies at river banks. There's restaurant too at hotel. If you prefer grill food you can find such at city center.
City center is between Juankoski trainstation and Stromsdal factories. It's quite small and it's quite easy to drive through it without noticing. If you unfortunately drive through it without stopping you lose opportunity to drink refreshments and try really delicious buns and pastries at Herkku-Vehnänen confectionery.
At city center there's also Juice Leskinen's square where you can see monument dedicated to this great finnish composer and lyricist who was born at Juankoski. Monument might be little hard to find but it's right next to the biggest shop in city center.
Nightlife happens mostly at Hotel Niskakoski and at Disco Marilyn.