My DH and I are both in our early 30s and have been going to Disney as a couple for 5 years now. We average 3-5 trips a year depending on the runDisney calendar, time off from work/school, and when our group of friends take the weekly trip. Our vacations are usually fairly laid back and we go at our own pace, but each trip, we (try to) do this:
Stay somewhere we haven't been together.
Drink around the world at Epcot.
Monorail/Boat pub crawl.
One meal somewhere we haven't been, ADR can be made.
One super fancy dress up dinner, ADR must be made.
Do a different activity each night.
Aside from these two meals, we do not make ADRs on solo vacation trips. Group trips and runcations, yes. It forces us to not be slaves to a schedule, but again, we go A LOT. You may want to eat certain places and ADRs are good for that.
When we go to the parks, we usually have our FPs and a short list of things we want to do. If we see a short line for a character, we'll hop in line and are sometimes the only adults without kids in line. We get in as many rides as we feel like doing, but if the line is long and we don't have a FP, we don't do it. If we go at the holidays, we tour the resorts and parks and get pics in front of every Xmas tree. If it's not a holiday or special event, we find as many PhotoPass people as we can and overdo it on photos. We also strike a specific pose per trip for most ride photos (ie, Christmas last year was the 'Home Alone' face).
We'll also try to find different locations to watch Wishes-- the beach at the Poly and the lounge at the top of BLT are two of our favorites (and convenient if we are doing a monorail pub crawl). One of my favorite Wishes experiences was having dinner in Cinderella's castle later on in the night and having the fireworks go off outside. You can't really see the fireworks from inside, but the windows light up, the stained glass looks awesome, and it was still pretty magical.
We also love going to AKL for the nighttime "safari" with night vision goggles (which might be just for people who stay there, not sure) and the campfire sing along. If you walk around AKL during the day, there are flamingo pools and lots of neat things to see. POR has carriage rides and Yehaa Bob-- a super fun piano sing along that is worth it if you don't mind being picked on or doing the YMCA in front of a bunch of random people. If you've got it in your budget, Victoria and Albert's is a fun fancy-pants dinner but isn't cheap and be prepared to be FULL after going. Kimonos at the S&D has karaoke and most of the singers (not me) can actually carry a tune. And if you're not afraid of heights, Characters in Flight is great... but I'm super scared of heights so I couldn't see the happiness in it. We were initially going to get married there, but I'm glad I re-thought that. I'm a wuss.
I could keep going and going, but it would be an even longer post.