Bonn, Cologne, Berlin, or ?

If you can get a direct flight into Cologne from any of these places, take it after comparing the price to Frankfurt, which should have lots of direct flights. Frankfurt Airport is almost as convenient as Cologne, as it is an easy and frequent train ride from the airport, direct once every 2 hours in 1 hour and 45 minutes. Walk-up fare is 50 EUR.

There is a direct bus from Cologne Airport to Bonn every half hour taking 45 minutes. Cost is a local network ticket, which is 6.59 EUR with the VRS app.

You could also consider Duesseldorf Airport, which also has direct rail service every hour. Takes 1 hour costing 25.80 EUR.

PS, If coming from Munich, a train is probably just as convenient, as it can be done in 4 3/4 hours, without any of the hassles of going to/from airports, security, etc. Fastest way would be a direct train to Siegburg/Bonn, then a tram across the river to Bonn.

Great info...TY Sam. Gives me a good starting point.

Omio web and app are a good start for such a question, comparing the various means of transport.

I recommend flying to CGN (Cologne).

TY Mark, Cologne would be a wonderful place to also visit, being so close to Bonn.

It is. Königswinter - opposite Rhine side of Bonn - with Drachenburg Castle and cable car is worth a visit.