SQL Server Checklists
Only variation I'd suggest on your check list is to replace the word BACKUP with RESTORE. Checking that backups complete is a good start, what really matters is whether or not you can restore from them. Alert on a backup failure, automate a random sampling of restores so you know your backups are good.

The next step on from a daily/weekly/monthly check list is history. A check on x/y/z performance counters is meaningless without a baseline to compare today with yesterday. Without understanding the today vs yesterday, it's impossible to predict next month.