1. How much vibration does it absorb?
The more it absorbs, the less sustain generally, however the absorption rate will not be flat across the spectrum.
Different woods will absorb different frequencies and harmonics. The result is different tones.
Hard and dense absorbs the least.
Soft and light will absorb the most.
It's the principle of "inertia," I think. The heavier and harder the guitar's body in proportion to the string, the less the string's vibration will affect it.
2. How much does it resonate?
Resonance is sympathetic vibration, or the wood's ability to "dance" to the string's note. This is very important with acoustic guitars. (Some kinds of spruce are very resonant, and used on acoustic tops. Mahogany is softer, therefore "warmer," more often used on sides or back. Lots of others.)
Resonant woods can enhance certain frequencies and harmonics. The harder (not heavier) the wood, generally, the more resonant.
3. How good does it look?
Purely psychological, but if that quilted maple gets you off, you play better.
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So weight by itself won't do much for you if the wood's quality is poor.
One cool place to check out some fairly strong opinions is Ed Roman's website. He makes some nice stuff, and when he trashes Gibson and Fender, you get the idea he knows what he's talking about.
Regards...