atropine

I have been out of touch in the car audio world for a long time now. I don't really have time to spend doing research, install, etc. So I need some quick help from those of you who are in the know currently. I am trying to decide whether to buy a Sport pkg and then upgrade the whole system with an aftermarket nav head unit (I have looked at a couple writeups here on this forum and they look very nice), speakers, and sub; or do I just buy a Sport+Touring pkg and either just live with it or add a simple sub to the factory Bose system. This will be my daily driver and I put on about 100 miles a day of freeway miles. I don't need an incredible system, but I would like something that sounds nice. I only spent a few minutes in a Touring pkg car at the dealership and noticed a significant improvement of the Bose stereo over the cheap base stereo. All I really want is XM radio, Bluetooth, and a decent sounding system. I listen to a lot of old 80's rock, and new hard rock stuff. No rap or really heavy bass music. I have a Blackberry now, but am planning to get an iPhone4 in about 2 months. I really want some sort of iPod interface with whatever system I am running, not just a simple aux input cord. I want to be able to toggle between playlists, songs, etc. using the steering wheel controls, and use the source button on the steering wheel to toggle between XM and the iPod. I don't really need nav, but if the iPod interface is significantly better with either the factory nav or aftermarket nav I would give it stronger consideration. I just don't know what the interfaces are like on any of these systems. I would also like to mount an iPhone holder somewhere in such a position that I can see the screen for incoming calls, etc. Any ideas? As far as subs go, I really don't want to use up any more trunk space than necessary. I like the enclosure that puts a sub in the spare tire well yet retains the spare tire. Can an amp be mounted under the rear hatch covering somewhere to power such a sub without having to move the spare tire?
Thx everyone.