Like you, I have always used Stan-HOPE-ee-uh, but as it is named after someone whose surname was "Stanhope", the AOS recommendation should be proper.
Then there's one of my favorites: neofinetia.
I have heared Nee-oh-fin-EESH-ah and Nee-oh-fin-eh-TEE-ah, but the French botanist's name is pronounced Fee-Nay, so I suppose it ought to be Nee-oh-fee-NAY-ee-ah