You can check in at A west.

There are plenty of kiosks there and the preferred lines are usually short because of the heavy morning tourist traffic to the caribbean.

Sometimes I will use A west to check in for B/C flights when things are especially chaotic over there. Folks for 700 usually start filtering in around 2pm so the whole place is typically pretty empty between 12-3.

That said, if you are parking and plan to go to the club first, I agree with hginPHL that it is easier to check in at B/C. Less of a walk to the car on the return.