Making suggestions, agreeing and disagreeing	

I agree up to a point.	
I am agree with your point.	
I can't really agree with that.	
I could go along with that.	
I think that is an excellent suggestion.	
I think we should accept the offer.	
I wholeheartedly agree.	
I'm not sure that would be a good idea.	
In conclusion we are agree.	
In my opinion we should accept the offer.	
So we all agree.	
So we're all agreed.	
That sounds a pretty good idea.	
That's that then.	
The best thing to do would be to accept the offer.	
Unfortunately I am unable to agree to your suggestion.	
We could accept the offer.	
We may accept the offer.	
Why don't we accept the offer?	
You can't be serious.	

Giving opinions	Strong 		tentative	
Informal

Neutral

Formal / written

I think we should accept the offer.

The best thing to do would be to accept the offer.

In my opinion we should accept the offer.	

Why don't we accept the offer?	

We could accept the offer.	
Agreeing and disagreeing	Strong agreement	Partial agreement	Strong disagreement	
Informal

Neutral

Formal /written	That sounds a pretty good idea.
I could go along with that.

I think that is an excellent suggestion.

I wholeheartedly agree.	

I agree up to a point.	

You can't be serious.*

I can't really agree with that.

I'm not sure that would be a good idea.

Unfortunately I am unable to agree to your suggestion.	
Concluding				
Informal

Neutral	That's that then.

So we all agree.
So we're all agreed.

The following are not natural expressions in English:
I am agree with your point.
In conclusion we are agree.
We may accept the offer.