Ideal wedding cake base diameter?

Can't be of much help to be honest, but when I told my lovely bridesmaid who is making our cake that the venues cake stand is 30cm she laughed and said we won't be using that then! We're going for 4 tiers

Could you use a log slice? I've seen quite a few on pintrest that look really good. We're having cheesecake (dessert) as our wedding cake and having each one on a different height log but you could just use one as the base x