How about… [ex. trying something new]?
Why don’t you… [ex. talk to your boss]?
Maybe we should… [ex. do more research].
I’d recommend… [ex. going to the doctor].
Have you thought about… [ex. buying a new computer]?
Do you think it's all right to do it?
What do you think about (me doing that)?
Do you think / reckon I ought to (do it)?
What would you say if I (did it)?
Would you approve of (doing something)?
What is your attitude to the idea of...
Are you in favour of (me doing something)?
You are in favour of ... aren't you?
Do you think anyone would mind if I...
Would it be really awful if I...