If you just select one of the guitar sounds as say upper1 sound it's going to be a pretty dry sound as with any sound. A good way yo build up sounds is to work your way through the styles and the 4 keyboard sets the accompany them. These will have had effects applied to them, if you find a sound that you like store it in your user keyboard set library. It's a good way of building a library of sounds. They will sound quite a lot different from the dry sound. You can also go through the songbook entries and do exactly the same.

Once you get familiar with your Pa1000 you can do a bit of reverse engineering and see what effect were applied to get a certain sound.