I’ve started using the following route for 1 hour workouts, and I think it would be really good for racing and especially TTT.
Start on the Ocean Lava Cliffside loop. After the cliffside, turn right to enter the desert before you get to the underwater tunnels. Stay in the desert until you cross back over to downtown to finish. It is right at 30 km and has a great mix of climbs and flats.