it's not very inviting to go on GitHub and see all the CPAN related modules

What an odd thing to think. I take the opposing view.

how much work and effort should go into customizing a release for GitHub as compared to CPAN?

Github is not a release channel, it is a publicly-accessible, managed VCS repository.

is Pod::Weaver the best way to autogenerate the pod or is it easier just to rely on a default template that you modify?

Autogenerating POD is lazy and not in a good way, so don't do that.

Also, some more basic questions: when do you commit to GitHub vs. releasing to GitHub and CPAN?

See above, you don't "release to github".

I was wondering if I could get some basic advice and hear how others are using Dist::Zilla/CPAN/GitHub to try to find an optimal software release solution.

Optimal in terms of what, exactly? Fewest bugs or most extensive documentation or easiest for others to contribute or efficient for you as release roller or most structured commit logs or ... ?

Perhaps it's time to heed what almost everyone has been suggesting and stay away from Dist::Zilla until you've answered all the questions you posed to your own satisfaction. It doesn't seem to be helping you. Good luck.