Ettlingen lies in the next zone outside Karlsruhe. So you need a 3 zone ticket coming to Ettlingen. If you plan to return within 24 hours to Karlsruhe, then you best buy a cityticket 3 zones for 4.20 Euro for one person. You can buy it from the driver or the ticket machine in front of Karlsruhe main station or the ticket kiosk. It you travel with someone then you best buy Cityplus ticket for 3 zones for 6.50 Euro. On this ticket up to 5 people can travel for 24 hours.
To reach Ettlingen Stadt take the S1 from Karlsruhe for about 15 - 20 minutes.
Ettlingen is well connected to Karlsruhe's public transportation network. The tram lines S1 and S11 take you from both Karlsruhe's centre and train station to Ettlingen every 10 minutes.
For the old town and the palace, get off at either "Ettlingen Erbprinz" or "Ettlingen Bahnhof" - I suggest "Erbprinz" because it is next to the palace and closer to the town centre. Ettlingen's old town is small and easy to walk.
Ettlingen is included in the Karlsruhe City Ticket and CityPlus Ticket because they are valid for 3 zones. It is also included in the WelcomeCard.
When taking the tram S1 or S11, get off at the station Erbprinz or Ettlingen Stadt. Both stations are within the actual center of Ettlingen. The Erbprinz is just next to the fabulous hotel/restaurant "Erbprinz" and right across the street from the palace and Ettlingen Stadt is the closest station to where I work.
The Stadtbahn takes you from Ettlingen to Karlsruhe main station in 13 minutes - or to Bad Herrenalb in the Black Forest in 20 minutes!
The trains are very clean and very comfortable! Be sure to buy a ticket and stamp it inside the train.
Ettlingen can easily be reached by bicycle from Karlsruhe. A marked bike trail follows the Alb river through parks and fields. The pleasant ride takes, depending on your speed and fitness, about 30-45 minutes. This first part of the trail is entirely flat with the exception of the bridge across the railway near Karlsruhe station.
The Alb valley trail continues further up the valley to the little spa town of Bad Herrenalb. That bike trip is more pleasant the other way round, though, in other words: downhill. Bikes can be transported on the tram for free after 9 a.m. So if you want an easy trip, take your bike on board the S1 to Bad Herrenalb and cycle back down the valley.
This trip is also suitable for untrained bikers or families with smaller kids - if any of the participants get too tired, hop on the S-Bahn, which runs more or less parallel, at the nearest stop.