Posted on 
Oct 22, 2007 11:23 am From what I've gathered, softer woods make for a darker sound. Harder, denser bodies, like maple will give a brighter sound.
Maple fretboards give more brightness as well, i've read. Rosewood is common, and ebony is another option. The best option, i've read in a few places. I prefer maple myself.
Neck thru can add to a guitar's sustain, but they are harder to find, i think due to it's difficultness to make cheaply. I should add, many neck-thru guitars are multiple pieces of wood, glued together, then cut to fit. My Excalibur is neck-thru, 5 pieces, side-by-side, then a rosewood fretboard on top. It's very stable, and doesn't loose tune very easily.
Bolt on neck is the cheapest way to go, i'd think. Set neck is a good in-between.
Another issue with electrics are the pickups. There are tons of options, of which prices vary accordingly. Humbuckers are more silent (hence the name) and offer a fatter, dense sound, whereas single coils can be noiser (some noiseless options are out there), and offer a cleaner, brighter sound. Country pickers often use telecaster (single-coils) due to it's jangly-type sound.
Some guitars are active, having a boost-type circuit on the guitar itself, along with a battery. These can boost certain parts of the audio spectrum. Eric clapton plays an active strat, with a mid-boost, i believe.
24 fret necks can be nice to play up higher, but not necessary. Fret size can be an option too, but often is not.
Neck radius is an option on fender guitars, but not all of them. Some necks have C shape, some a V shape, etc. I can't remember all of them =/.
