On arrival day, I always like to get our room settled - unpacked, organized, hang up clothes, etc. Take care of any "business". If we don't have park tickets, we will most likely visit Disney Springs or make a dinner ADR at a resort and spend some time exploring that resort, grabbing a drink, etc. On our most recent trip in October, we took an Uber to City Walk at Universal on our arrival night because we didn't have time to do Universal during that trip. So, we got a taste of Universal without spending money on park tickets.
On departure day, I prefer not to visit a park. I like to pack everything up, take our time, take in the last few moments of the resort. Depending on our flight time and DME pick up time, we may do a TS breakfast at a resort. We find visiting a park on our last day is too time consuming and we're constantly rushing and clock watching. I also don't like getting sweaty (if its hot) before our flight and I usually wear something different on the plane than I would to a park, so that's just another logistical consideration for me.