81,
What country are you from? What type of driving are you familiar with?
Residents of different countries have different regulations in other countries, much like visa regulations. Depending on where you are traveling from you may have a visa requirement to travel to various European countries, or you may be covered by Schengen visa waiver programme.
You will require, most likely, an International Drivers Permit in addition to your home driving licence. There is, for example, a new regulation on British licence holders renting cars in continental Europe requiring a the obtaining of a special PIN from the British government.
Driving in and around Paris takes the patience of a saint, and parking, where you can find it, if very difficult and expensive.
Driving in and around Brussels can be very difficult. Belgian drivers have a bit of a reputation, and my experience has not been good with Belgian drivers, especially in and around Brussels. The kerb stones are very high, made of stone, and the edges are sharp. Trust me. Virtually no car rental insurance covers tyre damage. Brussels drivers apparently disable their car's turn signals as soon as they buy them. Expect a driver in Brussels to suddenly veer from the fast lane directly across you without signalling to an exit ramp, crossing 3 or 4 lanes without apparently looking at all first, causing screeching of brakes. This is the voice of experience.
The Belgian road plan is very dense, as is the country (not the people, certainly not Poirot).
The speed limit in the Netherlands is quite slow, but that's OK because you won't always be going that fast. The traffic, particularly in the Randstad is very dense.
Brussels, Amsterdam, and Paris are certainly NO PLACE for a car. It is an albatross around your neck - an extremely expensive albatross.
Where are you flying into (CDG?) and where are you flying out of?
If you hire a car in France and want to drive it in German cities it will likely not have the legally required umweltplakette - the green sticker. You can't drive into most German cities and large towns without one.
The trains between Paris, Brussels and surroundings, Amsterdam and surrounding, are fast, comfortable, can be quite cheap, and very frequent. Big picture windows which are usually clean with much better views than you can get from a car in many places.