Solo travel to North Rhein- Westphalia region itinerary

I’m planning on spending five to six days on the region. In August I will be moving to Utrecht and I have some days before my apartment becomes available so I decide to hop on a train and explore this part of Germany since I’ve never been there before.

My plan is as follows:

Day 1: arrive to Düsseldorf in the afternoon

Day 2: Düsseldorf . I love art museums and I’ve heard that Düsseldorf has some pretty interesting ones so I’m planning on spending the day exploring them.

Day 3: day trip from Düsseldorf to Cologne .

Day 4: day trip from Düsseldorf to Bonn.

Day 5: train to Aachen

Day 6: explore Aachen

And the next day take the train back to Utrecht from Aachen .

I decided to use Düsseldorf as my base cause it seems to have the cheapest accommodation from all places plus it’s close to both Bonn and Cologne.
Do you think though that it’s worth it to spend a bit more and stay either in Bonn or Cologne ?
Is Bonn actually worth the visit or should I arrive in Aachen earlier and spend more time there ?

Any recommendations about things to do in Cologne and Bonn? Apart from art museums i love exploring neighbourhoods and experiencing a city like a local . I’m not a very big fan of architecture or palaces or museums other than art ones .

Solo travel to North Rhein- Westphalia region itinerary