My wife and I have toured with guides various times on vacation using closed deck kayaks. We are now ready to get serious about it. We have completed basic sea kayaking courses, with self rescue etc. We are in the process of demo boats to find the one which like. Now the opinion question...Do you recommend a composite boat (fiberglass, etc) or Poly boat for a first purchase? Money is not really an issue in that, I don't mind investing it in a quality boat which will last as our skills improve.

Composites are lighter which is nice for car-topping and carrying. Depending on your size and upper strength and your vehicle's size that can be an make or break issue.
Plastic is way more able to take a hit and withstand general boat abuse, dragging around on rocky shoreline, running into underwater rocks, surf landing, etc. You can do all this with a glass boat but you will be doing some fiberglass work to pay for the fun.
A better way to think of a first boat is get something that will work for a couple of years while your skills improve and you find out what kind of stuff you want to paddle. So I would argue for poly being a good choice. Something like a poly Wilderness systems Tempest or Zephyr. If you get out a lot, chances are the boat that feels good now will feel way too big and sluggish in a couple of seasons.
Most people I know started with a poly boat then after a couple of seasons, decided they needed something for racing or big trips or surfing or rock-gardens or tide-rips and bought a glass boat with a more specialized design.

Composite is better and faster with less effort. Way easier to load on roofs and two poly boats @ 65 lb each may exceed the limit of you rack system on the vehicle. If you are going to bang'em up then poly.

I am aware of the overall advantages and disadvanages of each type (wt, ease of paddle etc.) I guess it comes down to how much banging does a new boat take at the hands of a typical beginner. Any signficant horror stories related to your first boat over the first few years, which would make more of an argument for a poly? I guess I worried about spending the money for a nice composite boat, then abusing it more than normal because of the learning curve.

What sort of coast are you paddling?

We are always landing on stony or rocky beaches and "rock gardening" (shell fishing the other day). If your coast is sand beaches and weight does matter then definitely go composite. Some manufacturers (or they can in NZ) can turn out a poly boat as light as a glass boat so check that too. Polycarbonate (ABS) are definitely light and I'd put them halfway between glass and plastic for "bash-abiltiy".

Not necessarily "learning curve" for bashing a boat. If you are really experienced you might be taking more risks and bouncing in amongst rocks for the fun of it so the boat gets more abuse than a learner who takes thing cautiously.

We use wood and get round the whole problem, nearly as tough as plastic and lighter than composite.

Alex

How much abuse depends what type of paddling you intend to do. I don't think there is a learning curve for boat abuse. It probably gets worse if you progress in paddling and move to fairly dynamic water and/or rocky shorelines. Most damage I've sustained is where current or swell meets rock which beginners tend to avoid. If you make the effort to carry your boat into ankle deep water and not drive it up onto the beach you can keep a glass boat pretty nice for a while.
Either way, it's better to think of that first boat as training wheels rather than a long term purchase. A boat you find way too tippy today will likely be just right in a couple of years.

I chose poly for my boats. I have 2 Tsunami 140's, a Tempest 170 and a Nordkapp. All poly. I knew I wanted poly because I am going to abuse my boats. When I say abuse I only mean that I am going to hit, bang and scrap rock with my boats. It can't be helped. This is becuse of the areas I kayak. Although the poly boats are generally heavier and not as fast I was willing to sacrifice the pros of the composite boats for the "bashability" of the poly.
My Nordkapp is a very rigid boat for a poly boat.
Good luck and choose well.