I am back, so this is time for some reflections.
Amsterdam/Netherlands:
Fairly cool and very relaxed city. Plenty of weed in all forms and shapes, and you will consume (2nd hand) a lot even if you don't spend a single cent on it. There is plenty of the other trade too. It is cycling city but strangely all their bikes are total old rubbish. Just bring your own if you intend to cycle and serious distances, and make sure to take a very good lock. Don't expect to hire anything decent. Parking is about E40 a day so out of question.
Architecture is fairly uniform across the city; everything is built to the same plan. There is a big canal network, with cars parked near the edges, narrow stone paved streets and fairly tall old buildings. It is quite interesting, and can yield some nice sunset/sunrise pics facing the right direction. There is enough to look around for one day... Safety wise - no problems even in the red lights late in the evening. Just don't do anything stupid
There is one windmill in Amsterdam, but it is in a fairly crowded location. There is much better one in Haarlem (15min train ride). Haarlem is very quiet and picturesque (and free from the famous trades). It is almost an antithesis to Amsterdam.
Keukenhoff is well worth a visit even for a steep price. It is basically a huge botanical garden open only in the spring. There are some fields nearby, and they should be now in full bloom. I was a little too early this year. It is best to take the bike on the train or go by car to explore the countryside.
Paris:
That is one beautiful city, and unlike Amsterdam even 2 months would be too little there. It is enormous. There is loads to see all over the place, so I think it is a bit pointless to spend time listing everything, I'll just highlight the Louvre, Monmartre, Eiffel scaffolding, and the riverside.
Louvre has amazing collection of pictures, but it is also interesting itself - don't forget to look up and around. It is so big that even 2 days are not enough to see the whole collection.
Queues are massive everywhere. Entry to Notre Dam tower can take over 3-4h, same for Eiffel, etc. I couldn't be asked to wait for any of that when I could see other places.
If you are under 26 entry is pretty much free anywhere. No good for me though...
Safety - no issues again. Just don't leave the wallet sticking out of a rear pocket or a handbag and just keep it in the jacket's inner pocket. Louvre or busy metro trains (just fait for another) are your best chance to get lifted
Montparnasse tower is probably the best high sunset location (closed for sunrise) or Sacre couer tower. It is just a bit sad I didn't have a single picture worthy evening