I decided I couldn't handle the terrible audio quality from the stock headunit and speakers any longer.
I am in the process of buying the system, but the headunit will be the last piece since it is the most expensive.
After serious contemplation, I decided to go with a single DIN unit. I wanted a large screen, but I didn't want navigation. I use a TomTom and have lifetime map updates, and have very good experiences with it, and I have had very bad experiences with in-dash navigation units. The large screens look great, but without navigation my choices were severely limited, and the reviews were hit or miss.
This is my list of parts.
Headunit: Alpine CDE-HD149BT
Speakers: Polk Audio Mobile Monitor 6501 Components
Amp: JL Audio JX360/4 (Class A/B)
Accessories: Axxess ASWC-1, Axxess AX-SUBUSB, Monster Cable RCAs, and Monster Cable speaker wire.
I plan to do the install myself, and have had experience with it, so it shouldn't be a problem. I plan to mount the amp under the passenger seat, and then mount the speakers and tweeters in the factory locations for a factory look.
I am undecided if I would install a small sub in the future as I am not a bass freak, but I believe this setup will be a significant upgrade over stock.