I have found a simulator with some excellant pic examples both schematic and pcb layout can be generated as well as the code..... try Proteus.. its brilliant
for debugging, use MpLab.
But if you want to simulate a circuit with pic, the best is proteus.
So debug your pic's code with Mplab and see a global simulation of your entire circuit with proteus.
If you want to "learn" then you may want ot take a look at mICros, formerly known as PicnPoke.
It's for beginners, and do not require any microprocessor info. It has nice animated tutorials, an assembler you can use with your mouse, quizzez and more.
It's at http://www.bubblesoftonline.com/
An older version is available at BB's
FM, but the software is really very reasonably priced.
I have PicnPoke 2.61 and a keygen that works. Up from that version the author has cahanged the protection scheme, and I have not been able to find a cr@ck.