I just got my new rounded cables from Newegg, popped them in and amazingly my PC started up perfectly (usually when I fiddle with something good ol' murphy comes around and gives me a reason to fiddle more...), Speedfan reports no temp change but that's okay, I'm glad I did it anyway, if anything my PC looks neater inside now....which I guess doesn't matter since my case has no windows, but still....it matters....

Yeah them flat grey ribbon cables are just ugly...the round ones do improve airflow... though you have to route + ziptie everything up out of the way-- it just looks neater... more professional.

I use twisties that way I can undo them if necessary but I see where you're coming from.

I stick to the zip ties because the twist type have a thin wire in them and I have seen this cause problems in the past

I use green and yellow stripey electrical tape

I use small plastic cable ties for general use.

They come in pritty colour,s to.

They have all manner of stuff for this now:
Releasable zipties
Velcro wire ties
spiral-sleeving

These guys have an amazing assortmment 5 pages of just wire management gadgets:

Cyberguys.com - Cable Organizers, Cable Accessories, Computer Cable Organizers, PC Cable Organizers