Tomorrow has the same two actresses, Kim Hee Sun & Kim Hae Sook they both work well together in both series. Room No. 9 is about a soul switching event that changes the lives of both of the actresses. Tomorrow is about grim reapers saving souls. both have their sci-fi elements but Room No. 9 is limited in it's science fiction but it plays out pretty good.
I'm sure if you enjoyed one you'll enjoy the other.
I'm sure if you enjoyed one you'll enjoy the other.