I agree with arebelspy. Unless there are significant reasons (like an addiction) for one spouse not to have access to money, combining finances is the preferred approach IMO. You're sharing a life, most of your major expenses are shared, not to mention that whole "one flesh" thing (I know that's a part of my religious tradition, and I'm not trying to convert anyone, but it factors heavily into my own decisions and recommendations). Some other reasons to go joint:
-Chances are, one of you will always have a higher income, and keeping finances separate creates a massive possibility for resentment, which grows as the disparity increases.
-If you're on this forum, you're likely planning for FIRE, and it seems like it would suck if one spouse was financially independent while the other had to keep working.
-If you plan on having kids before retiring, one of you may want to take a pay cut in order to spend time with your offspring. If you keep the finances separate, that spouse may be less likely to afford doing so.
I'm sure there are others, these are just a few that come immediately to mind.
As far as structuring your finances... both of you should take advantage of workplace retirement accounts. Also both set up retirement accounts. Since tax-deferred or tax-free retirement accounts are designed for individuals, you won't be able to make these joint, but you can name each other the primary beneficiary of your accounts, and when you withdraw from them, it can go into your joint accounts. MMM wrote a while back about how he and Mrs. MM each set up individual investment accounts, and sort of competed to see whose profile was doing better. You could do that, or you could set up a joint investment account, but I'd recommend keeping your contributions uniform (ie, "we have $2300 to invest this month, so we'll put $1150 in each account).
For regular bills, just have them auto-debit straight from your joint account(s). For day-to-day stuff, use common sense. If you need to agree on individual spending limits, go for it. It's sort of understood in my house that the way we have the responsibilities divided at present, my wife is responsible for doing most of the spending (read: grocery shopping), because she's currently the primary caregiver, and therefore home much more, but the opposite has been true at other times in our marriage.