In electric guitars, the wood itself has a surprisingly small impact on the sound. I've built three electrics and been tweaking my guitar collection obsessively for more than 10 years. The pickups and bridge have far more to do with the tone produced by an electric guitar than the wood it's manufactured from. People never believe me when I make this claim, then I show them my Les Paul that sounds like a Strat and my Telecaster that sounds like a Jackson :) I get a lot of "WTF!?" looks and comments at open mic nights.
This obviously isn't the case with acoustic guitars.
My habit of heavily modifying guitars has proven very useful, as I used to sit in with a jazz ensemble that played a huge variety of types of music... If you're feeling adventerous, try reproducing my cheapo Epiphone Les Paul, which is now one of my most versatile guitars. Get a Duncan JB bridge position pickup, install it in the neck position, use your bridge pickup of choice. Rewire it so that there is a single master volume, independent tone knobs for the pickups, and use the remaining knob to dial the neck position pickup between fully-tapped and humbucking modes. That's the dirty trick -- tapped humbuckers usually sound too thin because they're wound less for the purpose of pairing up with another coil; with 0 on the knob being fully tapped and 10 being fully humbucked, I set it at about 3-4 and I get better strat sounds out of my Les Paul than I do out of my Strat (a 50th anniversary strat with Lace Sensors, soon to be upgraded to Lindy Fralins).
That said, violins are very different animals from guitars, and the varnish has a heck of a lot to do with the tone produced.
A common problem with acoustic instruments these days is methods of tree farming. Pick up a '65 strat, then pick up a 2008 strat. You'll feel about 4 pounds of weight difference, even though they're the same type of wood and same dimensions. Lots of wood used in musical instrument nowadays comes from tree farms, not from forests that have been growing for hundreds of years. As a result, a lot of emphasis is placed on fast tree growth, which produces less dense wood. There's a reason why old wood harvested from churches, houses, etc. is so in-demand for musical instruments.
Also, wood from old sunken ships is extremely popular (and expensive) due to its high density, and due to the tiny pockets of gas inside produced by bacteria consuming the wood. As the bacteria consumes the wood, it depletes the oxygen and dies off (wood does not rot in anaerobic environments). The little pockets of gas left behind change the frequency response of the wood and creates an incredible sounding instrument. Just tapping on such a piece of wood sounds like you're hitting a marimba.