Ken, someone my correct me on this, but I think the ticket for the taxi ride from BKK is to tell them to take the "express way", a few worth extra bucks.
Don't know if they fly to Krabi (tiny airprot) but Asia airlines has super deals you can get online.
I find that the boat ride to Tonsai/Railey is better from
Ao Nang than Krabi, and it is about the same time from the airport. Taxi drive from Krabi airport might seem expensive relative to other things. You can sahre w. others and the prices are actually set, not a rip off.
If you decide to take your gear, there is consigment at BKK airpot but give yourself an extra 15 or so.
Spendig a liitle more for a nicer place will be well spent but the selection for that in Tonsai is a lot slimmer.
I did go diving and the options are tons. Some cool spots, some murkier w. big schools of fish. Bring LOTS of sunscreen. Not the most amazing diving ever...but fun day checking out some small islands. (You might consider just climbing more, going diving in Hawai some other time...)
Can't remmember the name but there is an area in Pra Nang with a small gorge like spot with some sweet moderate climbs that are longer than average and less crowded, with a good approach for kids.
If any of your stuff gets wet, dry/air it right away, lots of people have mold problems (I haven't!)
Also my AT&T cell worked great and its cheap if you text.
Don't forget to get some cheap massage...
Sawatdeetka!