I use AVI with the Divx codec and it is as good as DVD quality and maybe better.
Try it, you wont be disappointed. Just make sure you render in the best quality.
i'm rendering to avi because the timeline has a substantial number of individual clips and fades (several hundred) and i can manipulate the piece much easier as one whole clip, rather than a complex veg. also vegas seems to work much faster with a few simple avi files, rather than hundreds and hundreds of short clips. i'm piecing together several video art pieces into one long timeline. is this a good solution?
Also keep in mind that if you have finished a segment and render it to DV .avi (any codec, doesn't matter which), then bring this rendered file into the timeline and make no additional changes, it will not be re-rendered! It will merely be copied to the new output file, so effectively you can use this file through infinite generations with no loss.
I do this all of the time. Work on a segment, render to NTSC DV avi. Work on the next segment, render to avi... When all the segments are done, start a "final" project and import all of the rendered segments. These segments will NOT be re-rendered except for where I overlap them. Rest easy, you are NOT losing quality this way.
concerning file size, does bringing these rendered avis into a new timeline affect re-rendered file size? for example, if i render several 2 minute vegs into seperate avis and bring them into a new timeline 5 - 10 times each, but only using different 20 second segments of 2 minute files, will vegas render the entire 2 minute pieces again and again, or just the 20 second segments visable on the timeline?
for that matter, the question holds true for any clip brought into a timeline. if i only use 5 seconds of a 45 second clip, does vegas render it with the size of 5 seconds or the size of 45 seconds?
Vegas only renders the part that is used on the timeline. For that matter, if the file you bring in is DV .avi and you're rendering to DV .avi, then any sections that are unediting or unmodified won't have to be rendered at all; they'll just be copied straight to the output file nearly instantly.