We went to SAARISELKA in 2019, same gig, will try and dig out the operator- firm we used, stayed in a lovely glass ceilinged cabin, lasers- heating? kept the glass roof cleared to enjoy the view...did see the Lights on our final night. I´d suggest wherever you go ensure they´ve got other activities so if you don´t catch the lights you´ll still have a great time over the 3 or 4 days, e.g. we sledded, drove dog sleighs, reindeer sleigh ride and show and tell, Guided night time snow shoeing into the lovely deep dark woods to look for the lights and a woodland shelter experience, drove snow mobiles ...also go with a firm that provides you with the arctic snow suits all inclusive, proper chilly up there. We loved it and our youngster is keen to return!
The wife tells me we booked through Arctic Direct and we stayed at Northern Lights Village, we did a half board package Breakfast and Dinner inc, didn´t really need more as the tables were groaning and Dinner was quite early.
Have fun.