Guilin Reed flute cave and Elephant Hill visit in half day

Can you let me know if we can visit Reed flute cave and elephant hill in a morning. We only have part of a day in Guilin and will fly to Shanghai at 5:00 p.m. We would like to take in a few sights before we leave. I know that we need to get to the airport two hours ahead but am not sure how the traffic is and how long it will take to get to the airport during the afternoon. Will it be faster by shuttle bus or taxi? Thank you so much for any advice you can give us.