In Dusseldorf 2 nights Cologne for 1 what is best way to get to Cologne/prices.
Take the train from the main station. It runs frequently and is about a thirty minute trip.
The price depends on which train you take. If you avoid the ICE trains (with have a surcharge for being fast trains), you should be able to go, one-way, for 12.5 euros or less.
In Dusseldorf, just go to any of the DB ticket machines. Switch it over to English and push the "Timetable" button on the screen. The machine will default to your location as the starting point and enter "Cologne Hbf" as your destination. Punch the "immediately" button for your departure and it will present you with the next three train options for your journey. You can select one and then print out the information and buy a ticket for the journey. The machines are easy to use and beat standing in the lines at the ticket offices.
there's three of us travelling would a Tagesticket be cheaper? I read a price of 33.90 is that each way?
I'm not very familiar with mutli-person tickets as I always travel alone and use a German Rail pass.
There are several multi-person tickets available. You can see them on the German Rail website www.bahn.com . Switch it over to English and click on the "Offers" button located at the top of the page on the red band. Click on "Travel Offers within Germany" and then select "Overview of Regional Offers" There are several options and you might find one that suits you best. Note that Cologne and Dusseldorf are both within the state of North Rhine-Westfalia and so the "Lander-Tickets" are worth examining.
If there's three of you, get an NRW Ticket, don't take any train before 9 a.m. (the ticket is not valid before 9 a.m.) and only take local trains. This would be the RE trains, but also the S-Bahn. Don't take an ICE, IC or EC train.
Time wise it doesn't make much of a difference. The ICE takes about 20 minutes, the RE about 30 minutes. I don't recommend the S-Bahn unless there's one ready to depart at the very moment you need it, because it takes about 50 minutes. (So better spend some time looking around the shops at the station and wait for the next RE train.)
To find the trains you can take, check "local trains only" on www.bahn.de
The NRW Ticket (the exact name is "Schöner Tag Ticket NRW") is EUR 41 for up to 5 people. I haven't heard of that other ticket for EUR 33. Anyway, that ticket would take you to Cologne and back, and you could even include a side trip to Bonn (to see the "Haus der Gechichte") or Wuppertal (to ride the suspension railway, "Schwebebahn"), if you wanted to.
we are staying over in Cologne transport there one day and back the next I assume that is two tickets needed?
From Düsseldorf to Cologne the VRS tariff applies (VRS price level 5). Single ticket is EUR 11,30. A mini group day ticket good for up to 5 persons traveling together is EUR 33,90. The mini group day ticket is however on weekdays only valid past 9am (all day on Sa or Su or public holidays).
Covered are all means of local public transport in and between both cities: regional trains, S-Bahn, Stadtbahn (mixture of tram and metro), trams and buses. Long distance trains like IC/EC or ICE or Thalys are not covered.
Yes, in that case, you need two tickets. So it would be cheaper to return on the same day, even if it's late at night. Normally, I'm not a fan of day trips, but Düsseldorf and Cologne are so well connected that it's not a problem at all. Unless a thunderstorm decides to flatten all the power cables again ...
can you use the VRS ticket on the return trip to go to the airport?