After I posted this, I was later thinking: "I wonder if Encore would support DV-AVI's, because that would actually be the simplest approach".
It sounds like it can.
I like that approach because I export DV-AVIs from each project as part of my workflow anyway.
The Automatic transcoding sounds a lot like the Elements functionality. Just give it some input, and it figures out how to best fit it to DVD. My projects are always under 60 minutes so I always just used "max bitrate" and it was fine.
I took a look at the bitrate calculator and half the things I had no clue about (e.g. does DV-AVI stereo count as one stream or two? What's my audio format?) Sometimes I like knowing the down-and-dirty details behind things, the rabbit hole of video and audio formats is not one of those things!
To me, it seems like bitrate and audio formats, etc. etc. is stuff the tool should be figuring out for me, not the other way around 