Any discussion like this needs to take place under the umbrella of one big general observation: how a modeler wants to build a model is that modeler's business. Personally, I'm a big believer in using a variety of materials as they are appropriate for the particular job at hand. That's why my little Hancock has a couple of dozen materials in it. Others take other approaches - and they certainly have every right to do so.
I think there's a pretty general consensus among experienced modelers that pine just isn't a good modeling material. It's soft, it's splintery, and it secretes sap (the yellow stuff - not tar, which has to be extracted deliberately). Here near the east coast, when we talk about pine we're usually discussing white pine; some dealers sell yellow pine, and a few sell heart pine. I can't recommend any of those materials for scale modeling purposes. (White pine used to be a favorite material of manufacturers of machine-carved, solid wood hulls, but those companies switched over to basswood or European whitewood quite a few years ago.)
Mr. Morrison makes an excellent point about wood species. Experienced modelers almost (not quite) universally reject the idea of using the prototype species in a model - unless it's on a very large scale. Oak, for instance, is one of the most common woods in wood ship construction, but it's a lousy wood for building models. (Hard as a rock, and with an extremely conspicuous, open grain. A 1/96 sailor would trip over the grain in full-sized oak.)
I can't recall having encountered walnut as a shipbuilding wood - except for ornamental carvings. Pine is, indeed, a favorite wood for prototype hull and deck planking. But I strongly recommend holly (if you can get it), with basswood as a good second choice.
Other woods favored by the present generation of serious saiilng ship modelers include cherry, apple, boxwood, and pear - all hard woods with very close grain.
One caveat about walnut. Serious American scale modelers rarely use it in actual ship models - though it's a superb wood for baseboards and cases. In Europe, though, lots of modelers make fittings and other small components out of European walnut, which seems to have a much finer grain than the American stuff.
Anybody who's interested in "taking the plunge" into really serious sailing ship modeling (from scratch or via extensively modified kits) would be well advised to invest in a miniature table saw. Mine is from MicroMark: http://www.micromark.com/microlux-mini-tilt-arbor-table-saw-for-benchtop-hobby-use,7500.html , but there are several other good ones on the market. The initial price is high (especially when you throw in some accessories), but believe me, the ability to cut wood precisely to your own requirements is worth the money. (Compare this thing to the prices of kits these days, and it doesn't look so bad.)
On the other hand, I used to have a full-sized table saw - the cheapest one Sears made. It cost me about a hundred bucks. With a "hollow-ground satin-finish veneer" blade, a homemade zero-clearance insert, and some patience in setting it up, I could cut really nice strips of holly and basswood as narrow as 1/32". The kerf of the blade, of course, was such that I was turning about half my stock into sawdust, but it was hard to argue with the results.
Being able to cut your own wood really takes the hobby to a different, and highly enjoyable, level.