Would this generally be related to too tight or too loose on the cassette ring lock? One thing I haven't checked yet.

I will keep checking everything I can think of. As far as the noise goes, definitely more of a creak vs. a click. I was out riding today and I can get the bike to make the noise basically on every down-stroke of the pedal (right and left).

Anyone know what I should be looking for to determine if the handlebars/stem is the issue?

Thanks!