I will give non-trivial advice - Sarawak.
Fly to Kuching from Johor - you can get one way flight for as little as RM60 (obviously no checked luggage) on AirAsia.
There - 2 days in Kuching - see the city, go for a day at Bako NP, eat seafood at TopSpot and other places, walk around waterfront.
Fly to Miri and from there fly to Gunung Mulu National Park - spend 2-3 days.
Come back to Miri for a day and fly to Johor.
No nightlife but plenty of exciting and unusual scenery and nature.