We've been using the following options for almost a year and really miss them now that we can't play live.
1. Equal turns
Yes, we are an experienced group.
We don't mind that it affects strategy of whether you buy the last Province or not.
The game already has that mechanic.
This tempers the huge 1st player advantage by offering duchies, etc. It's actually very interesting.
2. Approximately 3.5 to 4 Provinces per player
We prefer the game length of the 3 player game which has this ratio.
Whenever we use Colonies, we would use the same number of them as Provinces, but that's not as important.
3. No attack cards
This one is only for when one member of our group plays.
This could be a great option for newbies to learn with.
Could any of these become options that you could select in the online arena?
p.s. I tried to post this in Feature Requests, but couldn't