Make the reservations! We always make reservations and always notice how long the lines are when we arrive and are seated right away. At DL, if you don't make your reservation, they don't charge you for not coming. We've also called to say we are coming late a few times and they still hold our reservation for us. Also if you call in the am from your hotel, you can sometimes make reservations right then just in case.
When we went in March, we slept in one morning and called and got reservations an hour later. It was great. This past week, on Saturday no less, we were in the pool around 4 and the kids started getting hungry so I picked up the phone at the pool and called DINE and got reservations at Goofys for 5:20-perfect timing, the kids finished swimming and threw on clothes and off we went. There was a 90 minute wait for walk ups!!!
I swear I live by reservations-lol. I make at least one PS for each day just in case! It just seems so silly to me to stand in line for eating if you don't have to and we always prefer at least one "sit down and be served" meal each day to give ourselves a break or at least a character meal.