Thanks, Mrmiata! Problem solved.

I had been under the dash recently, as I had to repair the "sticky ignition" issue. Prior to posting this thread, I had torn the dash back apart and made sure all the wires were connected properly.

In the process of the repair, I accidentally broke my key fob into pieces and snapped the key into two pieces right underneath the rolling pin that holds the key in. I used vice grips on the key after the repair was complete, and drove the car five miles from my shop to my house (with the key fob in my front right pocket, right underneath the ignition). When I got home, I parked the car, threw the fob in the passenger seat, and walked inside. From then on, I have had this issue. Never even thought about the possibility of the fob being the issue, as I drove it home without a problem after the sticky ignition fix (but it must have been just close enough in my pocket, to still communicate with the receiver in the ring).

Walked out this morning, held the fob up next to the ignition as I turned the key, and it fired right up. I'll be ordering a new key from the Chrysler dealer today.

Being the IT & Operations Director at a global manufacturing company, I'm a little disappointed I didn't think of this on my own...

But thanks again!