If you’re not actually all that keen on Disney yourself and have little ones, you could absolutely get away with 1-2 nights and mostly focusing on the main park (Parc Disneyland), as this has more for the younger audience than Walt Disney Studios (though, I’ve always loved both parks since the second one opened!)
The pros of staying onsite are the extra magic hours (EMH) where you get to access the parks before those who aren’t in Disney hotels, a character in the lobby in the mornings who you can meet which is quicker than queuing in the parks and the magic pass (a pass which stores everything on one card: your room key, park tickets, group’s options such as meal plans and special events you’ve pre-booked and more).
Whether you have someone who isn’t too fussed on characters or you’re in the parks multiple days and saw the parade once, use this time to head to the rides as the queue times cut down dramatically.
Make sure you check out the Disney Village
Whether it’s the evening of the day you arrive, after park hours, midday during the lunchtime park rush or on the morning of the day you leave, you need to check out the Disney Village!