The 7 day AB ticket for €28.80 might be better value if you don't need the museum entry etc. with the Welcome Card.
If you're flying to/from Schönefeld you will need an Anschlussticket for Zone C as well but it should still be cheaper. Then you can sell it for €5 as a cheap 2 day ticket to some tourists at the queue for the machine when you leave, and get some of your money back.
The 7 day AB ticket for €28.80 might be better value if you don't need the museum entry etc. with the Welcome Card.
If you're flying to/from Schönefeld you will need an Anschlussticket for Zone C as well but it should still be cheaper. Then you can sell it for €5 as a cheap 2 day ticket to some tourists at the queue for the machine when you leave, and get some of your money back.