Ok, so I have to thank a-swift for helping me out as much as possible in messages, but I need some extra advice here from anyone using Adobe. Most of my vids are already MP4. I've already ripped them and converted them from DVD or I picked them up through a service. Anyway, I have a bunch of breaks remixes that I want to edit videos for (giving proper credit for the remixing artist(s) of course) and the way I've been doing them in Premier has been putting out pretty crappy quality. I import the files in, time stretch the original audio to match with the remixed audio for the video portion, and then pretty much chop away at the video until I have a finished product. When I go to Export, I have been exporting the file with the AppleTV preset at 640x480, 29.97, with aac audio, CBR bitrate of 3Mbps, key frames at 15. It gives me a decent sized file but I'm also essentially degrading an already compressed file and the output shows it.
Swift recommended I try an uncompressed format in Premier but the only one I've seen is QT YUV either 8 or 10 bit. Neither one will run in QT player (don't have Pro), or MPEG Streamclip. And AVI is only available on the Windows version. So I'm wide open to suggestions on how to do this. I would greatly appreciate any kind of help whatsoever. Thanks.

Just to update this a little bit for anyone else looking for help on this:
Sequence setup is DV 720 - 720x480 (.9091), 29.97fps, 48k Hz stereo sound, no field (progressive).
For export I created my own preset based off of the AppleTV preset. Multiplexer is set to standard, format is H.264, NTSC, 640x480, 29.97fps, AAC 224 48kHz, stereo. Field order is none (progressive), standard 4:3 pixel aspect ratio, level 3.1, CBR of 3.08, key frames every 15 frames.
I also apply the fast color correction and increase the grey level and either boost the red, green, or blue depending the video needs. Then I export. Hope this helps someone.