[tevake]

There are nice private accommodation offerings in most areas on VRBO etc. once you decide what area offers what you are looking for, check out those places. Most resorts are not humble or inexpensive.
Each island has a different feel. For natural beauty and low key fun in nature Kauai is hard to beat.

The big Island can be a bit more affordable and a bit more room to move around in and the active volcano, plus the most dependable mellow clear water for diving and snorkeling year around. This is where the black sand beaches are found.

Want a mix of nature and developed activities/ entertainment. Maui has both, and some good diving waters.

Getting into surfing may take more time than you think, not as easy as surfers make it look. But big fun once you start getting the hang of it.

Hawaii is quite seasonal as far as water sports are concerned, winter brings the big north swells that impact north and western shores.

Hanalei Kauai comes to mind as meeting most of you desires, if you can find a nice rental space available. A short drive will get you some good choices of snorkeling spots in Haena or Anini beach, rent bikes and you can enjoy all of Hanalei town and beaches. Some good learning spots for surfing along the bay beaches, the river there for some relaxing kayaking. But can be rainy there too.

So many good choices, Kailua Kona, Kihei Maui? have fun!

Cheers Richard