So I have been chugging along with Pinnacle Studio for my Dance Recitals for about 10 years now. The fanciest I get is to do some multi-camera editing, throw in a title & title music at the start of each dance.
I wash, rinse, repeat for 30 chapters. When I am all done, I put a Marker at the beginning of each dance, use PInnacle to create 6-item menu screen from each marker. The whole menu process takes 60 seconds.

Fast forward to 2017. I bought my daughter (and by extension me) a CC subscription. I have searched and searched about creating Menu's, but either the data is old or conflicting.

How difficult is it to take a 90 minute movie of 30 "chapters" and create a menu and then eventually burn to a DVD?

You have to use Adobe Encore CS6. You can download it through CC "previous versions" Adobe stopped supporting DVD authoring after CS6.

You have to install Premiere CS6 in order to get Encore.
Encore is a total different workflow to Studio: it does have a learning curve.
But in the end it will give you far better menu's.

In widescreen dvd Encore will not allow more then 18 buttons per menu page.
4:3 will take 36.