My family and I will be travelling by car next June from Netherlands to Paris. Our kids are 4 and 7. Does anyone have any recommendations for a good town to stop at along the way for a few days? We like the idea of smaller towns that are easy to get around, outdoor walks, swimming in rivers, good food, a few cathedrals / museums good for kids (especially since we will end up in Paris - that will be our city fix!).

It seems like there are a few national parks near Lille, so was considering using that as a base and doing a few day trips. Has anyone stayed at Lille?

Or are there an alternative smaller pretty towns? I've heard Senlis is nice, but very close to Paris!

Would appreciate any recommendations, thanks!

I always enjoy Lille and go there at least twice a year. But saying that doesn't really help, does it?

For a family trip, I would recommend driving along the Belgian coast, where there are all sorts of nice Flemish towns to stop with nice beaches, as well as unlimited frites and waffles. Continuing into France through Dunkirk, you can take the autoroute in the direction of Paris whenever you are ready, but you should go at least as far as Calais. I like the city itself and made a photo report about it -- http://anyportinastorm.proboards.com/thread/8028/another-calais?page=1

I particularly like the lace museum there. I am not at all interested in lace, but the industrial machines are outstanding -- Cité de la Dentelle et de la Mode - Calais Lace Museum | Any Port in a Storm

No town will have more than one cathedral, because a cathedral is the seat of the bishopric for an area. Small towns generally don't have those, but Senlis did used to be such a seat so has a cathedral. I wouldn't think kids that little would care about a cathedral per se, though. I haven't been there, but lots of people seem to like it so maybe that would work.

Lille isn't a small town, it's a very large urban area.

I liked Compiegne in that general direction, it's not too large, so you could call it a town but it's not a super small town. I thought it an attractive town, and it does have several museums or places of interest to visit. The forest of Compiegne is wellknown and nice for recreation nearby.
https://www.francethisway.com/places/compiegne.php

It doesn't have any cathedral, but it has a couple churches.

And of course near Compiegne, there is Pierrefonds.

Pierrefonds without Merlin | Any Port in a Storm

I would recommend Senlis and Chantilly. You do need to understand what a cathedral is. It's not just a big church.

Few European rivers are fit to swim in but many towns have municipal swimming pools open to all so if weather is warm swim outside if not they have indoor pools.

I rather like kerouac's idea of Belgian North Sea coast to Dunkerque and Paris - water might be too col but kids just love playing on sandy beaches. And could do a day trip to nearby Bruges and do a boat ride thru canals of this lovely ancient city. Though cities like Chantilly and Senlis and Compiegne are nice smaller cities - But, a beach would be neat for kids and towns like Blankenberge and Oostende are really neat places as are any of a number of towns.

Brugge would be nice - and take a daytrip to the beach by train if the weather is good. You could stay at the seaside, but it's always a bit of a risk, weather-wise.

I see you have a car; no need to take the train then, it's easy enough to park at the seaside in June.

Pal, there are plenty of extremely clean swimmable rivers in Europe.

The week in June 2018 we visited the seaside in Belgium it was impossible to park for most of it's length. Packed.
Not my favourite stretch of coast anyway as it is so over built, which is a shame given the beaches.
The coast past Calais is lovely and you could drop down to Paris via Abbeville.

Why not go further south through Champagne? Laon is worth a visit as is Reims of course. Or go through the belgian Ardennes, where there are most certainly rivers worth swimming in.
A lot depends on from where in the Netherlands you are setting off, and how many days you have available to you.