I'm not a big Karaoke fan, but one plus about singing in Hawaii is that one can sing Hawaiian songs. They also have songs in Japanese, Chinese and Tagalog. Another plus is the courtesy they extend allowing you to bring your own food and drinks into the room.
The Karaoke Hut has a number of private rooms starting at $35/hour. The rooms are clean and they have a good selection of recent songs to sing. For the brave, they also have a public microphone to sing in a bar like atmosphere. Karoke Room 2 has ten private rooms starting at $35/hour. The rooms and song selection are comparable. On Wednesdays ladies get 30% off and Sundays families have a 30% discount. They open at 2pm, but discounts begin at 6pm.
909 Kapahulu Ave
Honolulu, HI 96816
Karaoke Room 2
1680 Kapiolani Blvd, #105 (next to 24 Hour Fitness)
Honolulu HI 96814