On an E175, there overhead space for a normal rollaboard so long as you don't dawdle getting on. On the CR7, you will need to green-tag it unless it is quite thin and narrow as the size of the bins is quite small.
As to underseat storage, there is some, but if I recall, for at least some versions of both of these planes, the aisle seat on the side with 2 seats, the underseat support splits it in about half, making putting anything larger than a computer bag a little difficult without infringing on window seat person's storage area. Thus if underseat storage is important to you and you can't get the side with only seat, you may want to choose the window seat..