Germany - Mainz/Cologne Trip

My choices are an overnight train to Cologne and staying there 3 nights and focusing my attention on Cologne. Never been to either so I wanted to see what you think of those cities Or staying 2 nights/days in Mainz and 2 night/days in Cologne. Also is there buses that go from Mainz to Cologne? Thanks!

Mainz is nice if you are in the area (because you have a flight from FRA for instance). But I don't think that it is worth the 200km or so from Köln (Cologne), unless you have a specific reason to go there.
Why don't you combine Köln with Düsseldorf for instance?

Here is some info about Köln I found useful: http://www.flyertalk.com/forum/germany/1151040-cologne-any-info-please-travel-places-go-eat-etc.html

Cologne is a great city. There are Roman ruins there - you can actually walk in the old Roman sewers under the streets. There is a great Roman museum there. Of course there is the Dom, which is spectacular. And there is the chocolate museum (and shop), which I really enjoyed. At Christmas, there are at least 5 Christmas markets in the city.

So if you had to choose between 3 nights in Cologne and 1 in Mainz you would take that over 2 and 2? Is one full day enough to get the jist of Mainz itself and spend more time in Cologne?

So if you had to choose between 3 nights in Cologne and 1 in Mainz you would take that over 2 and 2? Is one full day enough to get the jist of Mainz itself and spend more time in Cologne?

I would stay 1 day in Mainz, 1 day in Bonn and two in Cologne. The three places are all on the same train (main) line, so it is an easy journey.

I would stay 1 day in Mainz, 1 day in Bonn and two in Cologne. The three places are all on the same train (main) line, so it is an easy journey.

I would have to agree. I definitely wouldn't bypass Mainz. I just love that town.

I also like Mainz, but Cologne has considerably more to offer. For example, the Museum Ludwig in the latter is worth several hours for any fan of modern art.

A whole day in Mainz is more than enough. The city is small and compact and there really isn't that much to do after a whole day (or even part of one).

A good and scenic way to get to Koeln from there is via K-D ferry.