We have only stayed in one or two aires so far but might give more a try as we see them. We do like setting up with chairs etc especially if the weather is nice but certainly worth trying for journeys - especially as my income is now going to be reduced!!
We like St Lambert too - and with an ACSI Card, at 12 euros per night between 01-05-2020 and 03/07/2020 and again from 24-08-2020 to 28/09/2020
with seven nights for the price of 6, or 14 nights for the price of 12, it's really good value