Sadly we are unlikely to ever have a Best of Series as it means teams (especially those in Arenas) having to book and pay to hire their venues and might not need to use it.
It's sounding increasingly likely that it'll be three conferences of four teams with a 4xH&A and 2xH&A split. And so to ensure fairness you'll have to make the non-Scottish conferences as even as possible. Which is a shame as I like the "Conference of Fire" idea with Devils, Blaze, Lightning and Flames.
To keep it even and remotely geographical the best solution I can come up with is:
Scottish: Braehead, Dundee, Edinburgh, Fife
Northern/Midlands: Coventry, Manchester, Nottingham, Sheffield
Southern/Irish: Belfast, Cardiff, Guildford, MK.
Belfast probably wouldn't be overjoyed at the prospect of trying to sell tickets for 8 games against two new teams. But based on the "If you all hate the Devils clap your hands" chant from the playoffs they now see us as a big rival.
What I would then do is change the format of the Challenge Cup. Four groups of three teams with the top two from each progressing to the QFs.
And to ensure more variety of fixtures (so you don't play your conference rivals a 5th time) I'd draw the groups so each group has one team from each conference.
e.g:
A:Braehead, Coventry, Belfast
B: Dundee, Manchester, Cardiff
C: Edinburgh, Nottingham, Guildford
D: Fife, Sheffield, MK
Which if my maths is correct is a guaranteed 30 home games season - the same as we had this year.