Separate accounts. My wife has a small business and pays herself depending on the month and my salary is regular so I don't want to mix my money with hers, sometimes she pays herself erratically. We each have our own Roth's, I have a 401K, and we each pay our share of the bills. She makes about 2 1/2 time more than me, so we each have a savings account and we also have a joint savings account we use to save up for vacations etc. My employer provides insurance so technically I put more money into the bills, but we do alright as we have no kids and no bills except the house payment which will be over soon.
When she retires she will sell the business and we will use that to buy a new home wherever we decide to retire to, most likely AZ.