Matthew Reed wrote:

Any suggestions on whether I should go 8' apart versus 6'? 6' I
understand gives stronger fences, is 8' apart good enough?

8' obviously requires less work.

6' is sturdier.

Consider the wind.

If you go with 8', pay particular attention to sagging. I'd put diagonal
2x4s to brace the top runner. Even so, the diagonal has to be cheaper and
easier than 25% more posts.

Also, for me, I'd use metal posts. Cheaper, smaller holes to dig, less
concrete, last longer, easier to replace, variety of brackets to attach
various things.

One more trick: Buy the pickets and store them in your garage for a couple
of months. Allow for plenty of air circulation to dry them out (use a fan).
If you install them fresh-from-the-store, when they DO dry you'll have 1/4"
(or more) gaps.