Ernest, feel free to look us up when you visit the Big Island. It would be fun to give a little tour. There are lots of private mind-blowing gardens on the Hilo side.
I've only been to Kauai once and didn't go to the arboretum... I'll have to check it out if there is a next time. I've only been on the Big Island for four years and I still don't know the names of all the different areas... a local will say "I live in.. blah blah blah" (Insert Hawaiian name of your choice) and I will have no idea where it is.
One thing about living on the side of a volcano at an elev. of 2,200 ft. is that I have not been able to grow one of my favorite flowers of all time... plumeria!!! You can pick plumeria from the side of the road anytime, but I still want to grow my own. Thank goodness tabernaemontana, gardenia, night blooming jasmine and champaca grow well here! Ooops sorry.. I think I've gone off topic!
But yes, there are a lot of boring hibiscus grown as hedges here. My boyfriend's Vermillion Queen is what got me googling exotic hibiscus... and it was this thread on Palm Talk that lead to my discovery of HVH (I posted a link to HVH's website).
http://www.palmtalk.org/forum/index.php?showtopic=30196