Are you turning gain down, maxing mids, and double tracking?
If you aren't, then its going to be hard to get a really good tone. To capture that sound you hear in the room, you have to actually change what you are hearing to get it to disk, your ears aren't the same as a microphone, and do you have your ear right next to the speaker every time you play?
I always record with gain about 30% less, if not closer to 50% less than I usually use, absolutely crank the mids if they aren't already, and do about 4 tracks of guitar (two panned left, two panned right, to make it sound like two guitarists).