If you want to keep separate iCloud accounts and still share some data, you can do this by adding each other's iCloud account to your devices as a second ("secondary") account. Secondary accounts can sync mail, contacts, calendars, reminders and notes.
To add your wife's account as a secondary account on your iOS device, for example, go to Settings>Mail,Contacts,Calendars>Add Account>iCloud and enter her ID and password. Then, to sync her notes, turn Notes on in this secondary account.
To add her account to your Mac as a secondary account, go to System Preferences>Internet Accounts (or Mail, Contacts & Calendars)>iCloud.