I edited a sequence in Final Cut Pro and it looks the way it's supposed to - aspect ratio wise. (16:9)
I chose export with Compressor, using a 90 minute, best quality, 2-pass setting. That automatically chose 16:9 as the aspect ratio in the Inspector, and I couldn't change it if I wanted to. (I'm assuming it read the sequence and applied the correct aspect ratio.) I started to get nervous, though, when the Compressor preview was displaying the video in 4:3.
I went ahead and submitted it, anyways, then imported my audio and video into DVD Studio Pro. My pref's there were set to 16:9, and so I just threw the files onto a track and burned a test disc. Now, I've got a 4:3 television. I thought that a 16:9 DVD would play 16:9 on my TV, and have letterboxing at the top and bottom, but it plays 4:3 and the video is squished!
It plays 4:3 on my Mac, too, so there's a big problem - not to mention the video quality isn't so hot.
I'm obviously missing a vital step here, (or two) but I can't figure it out, so any assistance would be greatly appreciated.
You can always change the Automatic settings, you just need to click the gear to the right first. Normally I don't let anything go auto, but that is me. You do want them to 16:9.
If DVDSP you need to make sure that the video is correctly flagged as 16:9 in the inspector it needs to be set as 16:9 letterboxed. The preference setting is how it will encode QT files not how it will display m2v files.
From what you describe the video is flagged as 4:3.
As for quality I have posted guidelines mostly in the DVDSP forum so you can do a search over there if you like.