This has probably been suggested countless times before but here it goes again...
How about a Swiss Banded Tournament? Group of say 20 players similiar strength, open draw first round, then normal swiss rules from there for 6 rounds. I realise it could take an age cos round 2 counldn't be drawn until all 1st round games finished but it would be worth the wait (maybe!). I like the idea of playing someone in competition just once as happens in OTB competitions.
The advantage of swiss style tournaments is that you can find a winner among a field of 20 to 30 within 6 to 8 rounds. Because here we can play multiple games at once if you split that field into groups of 4 you can have a winner in perhaps 3 rounds (assuming there aren't a huge number of drawn groups and the final round is decisive).
Another advantage of a swiss tournament is that you can have a field with varied ratings and have class winners. We have banded tourneys for that here.
EDIT: It's not that I think swiss style tournaments are bad but I just think that they don't have any advantages in correspondence chess.