Starting problem

Last month we ran some errands in our 96 JGC Limited and after making a few stops we can't get it to start. The system has electrical power and when you turn the key you can hear the relay box click, but the starter doesn't engage at all. We left it an hour, tried again - no good. We left it overnight and the next morning it fired right up. It has since happened twice, and both times if we let the vehicle sit overnight it fires right up. The starter engages/disengages fine, so it doesn't sound like it is going out. I have traced most of the wires from the starter and they all seem solid, the junction boxes are tight. Wiggling the wires doesn't hlep, replacing the relay didn't help. So far, only leaving it overnight seems to fix it.

Any suggestions?

The next time it dosent start try jumping it with another battery. If no go try starting it by jumping the starter. Your solenoid might have a short when it is hot wont start and when it cools down it will restart. Make sure the battery and starter connections are clean. Other things to look at are nuetral saftey switch. Try moving the shifter to neutral and start. I think the problem is in the solenoid or starter but could be the Battery.
I had a Z28 that wouldnt start when it was hot turned out to be a short in the Battery.