Here is a list of some of my favorite things on Kauai:

Breakfast:

NoKa Grill (Yum!) -- I share the parking lot with them! 

Lilikoi's (Lihue)

Olympic Cafe (Kapa`a)

Tip Top Cafe (Lihue)

Daddy O's (Lihue)

Lunch or Dinner

Rob's Good Times Grill (Lihue)

Duke's (Lihue, right behind my shop)

HukiLau Lanai (Near Coconut Marketplace, our favorite!)

Bubba Burgers (Poipu and Kapa`a)

Savage Shrimp (Poipu)

Keoki's Paradise (Poipu)

Olympic Cafe

Chicken in a Barrel (Waimea, Kapa'a, Hanalei)

Brenneke's (Poipu)

Golf

Hokuala

Puakea

Poipu Bay

Wailua (County Course)

Kiahuna

Makai 

Kukuiolono

Boating / Sailing Trips

Holo Holo Charters 

Blue Dolphin

Kauai Sea Tours

Capt. Andy's

Makana Charters

Beaches:

Kalapaki

Po`ipu

Salt Pond

Brenneke's

Hanalei

Lumahai

Polihale

Ke`e (Permit Required)

Kealia

Anini

Snorkeling locations:

Lawai Beach - For the experienced snorkeler

Ke`e Beach (Permit Required)

Poi`pu Beach

Lydgate Beach Park

Tunnels Beach - For the experienced snorkeler

Lehua Rock (Available through Holo Holo Charters and Blue Dolphin)

Salt Pond Beach Park

Anini Beach (Honu, or Sea Turtles)