Below are the formal and polite equivalents (synonyms) of 'think about' which you can use in your business or professional pieces of writing:
The synonyms of 'think about' below are used when you think about doing something before deciding what to do.
It has the same meaning and uses as 'think about'. To say that you did it for a long time, add 'at length' after it.
'We have considered your proposal at length and we have decided...'
It means that you have 'thought about' or 'considered' something very carefully and for a long time.
'We have deliberated on what we should next do with the project and we have decided...'