There are taxis - you walk out from luggage claim, cross over the first few lanes to a median that separates them from more lanes going the same direction. That's where the taxis come. There are usually people there to help guide the line to the next taxi as it drives up.

On the upper level, there are buses that go to Waikiki (#20 and #19 but make sure you check the sign on the bus because both directions follow the same route through the airport). But normally buses won't take big luggage though I've seen exceptions if the bus isn't crowded. Also, that late you have fewer options.

On weeknights, bus 19 comes through at 11:01, 11:31, 12:01. It is 8 minutes later on weekends.

Bus 20 doesn't run that late. But like I said, trying for the bus (just $2.50 - exact change only) is risky.

If you do take a bus, you may want to ask the driver to tell you when you get to your destination.

Not sure what a taxi would cost. I think the last time I took a taxi to my home, it was around $23 - 26 plus tip. I live 5 miles from the airport. Waikiki is probably more like 7 or so miles from the airport.