My personal faves include:
Kittiwake - so well prepared inside that even new divers can safely penetrate. plus schooling jacks and occasional massive grouper encounters outside.
Big Tunnels - killer swim-throughs with tarpons hunting inside
Grouper Grotto - shallow and entertaining maze of swim-through tunnels with lots of tarpon lurking in the shadows
Pat's Wall - pristine wall dive with giant sponges and plentiful tropicals
Ghost Mountain - giant pinnacle crammed with awesome macro life that you'll want to swim endless laps around
Eagle Ray Pass - for - you guessed it - eagle ray encounters
Babylon - another killer pinnacle dive with heaps of black corals and super fishy
Little Cayman - IMHO Bloody Bay Wall is the bes diving in the caribbean - every site is great - Mixing Bowl, Lei Lei's Lookout, Randy's Gazebo and Jackson Bight are highlights
And if he can get to the Brac, the Tibbetts wreck is awesome. it's big and broken in half to allow easy penetration
Just remembering all of the awesome dives I done there got my wanderlust cooking.
Here's a great web resource divecayman.ky
indove with dns divin for 3 weeks, i was there on march. and i was lucky to dive south, west, and north this time.
but i have been there 4 times and my favorite are, on the south definetly chinesse garden.
on the west i will said north west poinand orange canyon are the best, but also bonnies arch and the kittiwake
on the north i love agle ray pass, and creole cliff.
i recommend to dive with dusty and his crew, you can find then at www.divedns.com , they do small groups, with excellent dive boats.
i hope this info works for you.
wish you good bubbles