I'll be there for a conference in early April, and the options are given as "rent a car or take a taxi." I have to believe that there are other choices, and would appreciate any information. Thanks.

Depends whereabouts in Potsdam, I suspect. You can get to Potsdam by public transport:

http://www.fahrinfo-berlin.de/Fahrin.../query.bin/en?

It's fairly easy, you have 2 options that need just one transfer.

At Tegel airport you buy a ticket for fare zones ABC for less than €3. You can do that at a manned desk, vending machines, or from the bus driver.
It will be good for all transfers you need.

Bus 109 to S-Bahn station Charlottenburg (the display in the bus will say "S Charlottenburg")
change to elevated S-Bahn
S7 to Potsdam Hbf (main station)

or

Bus X9 to Berlin Zoo station (terminus of bus, so no worries to get off at the right stop)
change to S-Bahn (follow "S" signs)
S7 to Potsdam Hbf (main station)

There is more than one S-Bahn station in Potsdam, so one would have to know your final destination to tell you where to get off the train.

"There is more than one S-Bahn station in Potsdam",


I'll be in Berlin for a week in July.
Although it is my third visit , I am yet to see the Palace in Potsdam. If I take S7, what stop is closest to Sanssouci? Thanks.

For Sanssouci palace you take S7 to the terminus, Potsdam Hbf.
There you change to bus #606 to bus stop "Schloss Sanssouci".
Bus #606 serves all the sights at the Northern and Western edge of the park like also the dragon house, Orangerie, New Palais.

There is also a local train station "Potsdam Park Sanssouci".
But that's at the Southern edge of the park and not close to the palace. It would be more suitable if you wanted to stroll through the park, visit New Palais, and eventually end at the palace.
You reach that station once an hour directly with RE trains from the major train stations on the elevated cross-city mainline. Another connection per hour requires a change at Potsdam Hbf to another local train.

thanks Cowboy.