I'd like to suggest a new Play Order option that combines aspects of Freestyle and Sequential.
The Problem:
I love using Freestyle in casual games because I can take my turn at any time during the round. It speeds up the game a ton. However, I hate it when other people take their turn at the same time as me. The map does not refresh in casual, so I often get a big surprise when I'm planning out my attack only to have it come back as "Invalid Assault" when the territory I am attacking from is suddenly conquered by another player. Also quite often they'll sneak guys through a weakness in my defenses before I can move my reinforcements into place. It really makes me wish only one person had their turn at a time, so I could spend some time planning and not worry about sudden changes in the map.
The Solution:
Introduce a new play order that's first come first served. It would behave exactly like freestyle except that when one player hits Begin Turn, no other player can begin their turn until this player is finished. This is different from Sequential because players can take turns in any order in a round.