We have a big difference in our incomes (over our marriage I've brought in at least 5x more than her, and her income presently is < 30% of mine). We just put it in a joint account and then pay an equal "allowance" to ourselves every two weeks (my paydays, for ease of scheduling). It's about the simplest it can be.

The vast majority of the spending is out of that joint account. The allowances are mostly a hold-over from when she had no job (moved to the US on a visa, had to wait for the work permit and then to find a job, almost a year) and felt the need to ask me for permission to spend money. I was getting annoyed, she was getting resentful, we made the allowances so there'd be no questions. We both got the same, we could spend it without asking, spending for ourselves out of the joint account was allowed but always with discussion (mostly, "Can I?" and then "Yes").