The rear speakers are difficult to replace because of the plastic housing so I went with the direct replacement from continental_imports who ordered them for me using the Blaupunkt.de website as a guide. Great for your rear passengers but you won't here them without screwing up your stereo imaging so you might not want to bother with them.
For the front I went with the Polks you probably saw at crutchfield. Had to do away with the mounting of the old speakers and screwed them into the deck. The front deck has a metal backing underneath its surface that needs to be drilled through otherwise the screws won't get anywhere, and I used some foam insulation on the speaker borders to compensate for their uneven borders and help seal the air from the back. Produces clean tight sound from my as is Kenwood excelon.
Hope this helps in some way....