Putting my two cents in, if you don't mind my doing so.

I think booking specialized quality tours/guides needs to be done as far ahead as possible. We all share information pertaining to guides and services. Other boards and individuals, do, as well. Imagine if everyone waited until they got off the ship and expected to tour with highly sought after guides at a moments notice. You simply couldn't.

The tours you get at the dock are usually the group bus deals that, quite frankly, can be pretty schlocky! Any private guides waiting at a dock I'd be leery of. Just my opinion.

We booked Island Wings, Coastal Helicopter and Capt. Larry back in 2002, after I endlessly researched private excursions for our Alaska cruise. Outstanding experiences that we would have never had, had we not have booked months ahead. Same holds true with every guide/touring company we've booked with since, whether it be Alaska or Europe.