Help needed to plan cathedral/abbey trip to Northern France

I love this plan because I love that medieval church architecture. It seems like a doable trip in the eight effective days you have, though you won't have time for much more than the actual buildings, i.e. not much general sightseeing or loitering in the cities. If possible, I'd add the Romanesque cathedral at Bayeux (and the tapestry next door while you're there). And, if you haven't seen it and don't mind going into the northern suburbs of Paris, the basilica of St-Denis, the first Gothic church and burial place of most of the kings.

Take a map and put a dot on each city, then figure out a logical efficient route. It could begin and end at CDG if you can bear to miss Paris altogether. Use Via Michelin to estimate times and distances, keeping in mind that it doesn't account for traffic or stops or weather, i.e. everything will take longer. I haven't tried to do this but it shouldn't be difficult, and I expect your overnight stops will sort of present themselves.

Reims is a magnificent Gothic cathedral, where the kings were crowned, but keep in mind that it was largely rebuilt after being bombed in the First World War. I assume they tried to restore it as it looked before, but I don't really know.

Vezelay is an outstanding Romanesque basilica in northwestern Burgundy, but probably best saved for your next ecclesiastical exploration, south of Paris.

Very much agree with Dick putting Saint-Denis on your list! About abbeys is not to miss the Cistercian Royaumont Abbey, not so stunning as the Fontenay Abbey in Burgundy, but to my opinion the most beautiful one north of Paris.

Last April I have explored the area between Compiègne and Paris.

There are a whole lot of lovely tiny places between Paris and the places on your list. Close to Soissons lies Septmont, visited only the latter. You can consider a detour to Coucy-le Château-Auffrique if on the – N2 – way from Soissons to Laon. Longpont and it’s abbey between Soissons and Villers-Cotterêt is worth a place on your list too. In the latter you can visit the tiny Alexander Dumas museum, the background about this writer is very interesting to learn. Still regret not visiting Crépy-en-Valois as I think the old part of town around the abbey there is lovely. On the way from there to Compiègne Morienval Abbey and the adjecent rose garden.

The ruins of Chaalis Abbey are worth a look, but as I was running out of time I saw them only from the entrance. Think worth a visit if it happens you are in the neighbourhood. Nearby Ermenonville (Jean-Jacques-Rousseau Park) is nice for driving through or a stop.

Knowing it is an 19th century rebuild of a medieval castle I can’t get enough of Pierrefonds, have visited the place 3 times…. The inside of the castle is a bit empty, but has some items about the reconstruction by Viollet-le-Duc, who restored many prominent landmarks in France and making the idea about reconstructing this castle interesting to my idea. Btw Compiègne is certainly worth a visit too and not only the huge palace there.

To maximize your trip best is using a car. Roads close to Paris are as everybody knows (very) busy, but for instance the N2 from CDG to Soissons was pretty hassle free. There are some road works going on and maybe rush hour can give some delay, but to my experience not much to worry about.

https://www.royaumont.com/en/the-abbey
http://www.abbayedelongpont.fr/abbayedelongpont_fr/un_site_d_exception

Perhaps the ruins of Abbeye de Jumieges would fit into your trip.