Your friend wants to go for a meal,You don't like the restaurant he suggests(How about)
How about going for a pizza.
Your friend lost her Presentation and the meeting will start after one hour.(Why don't you)
Why don't you check your email if you have a copy / sent it to your boss .
You see tourist, she lost her bag and doesn't have money.(Why don't I drive )
Why don't I take to the police station?
Your friend has to write a report for her boss but there isn't enough time .(Maybe you should)
Maybe you should call your boss and tell him you need more time.