1. I've been going solo the last few years. While it would be nice to have company, being solo has allowed me to do things I otherwise wouldn't if with others. Like you, before going solo I had been there a few times over the years. As a kid my parents dictated where/when for everything. And when I was older I was at Epcot with some college buddies the day before a friend's wedding. There too I didn't really do what I wanted. As a bunch right out of college, everyone was there to have a few drinks and leave, especially since we were there for free and no one cared about doing anything (one friend was a cast member who gave us passes)
2. You will enjoy doing what you want, as often as you'd like, and skipping what you don't want. Ride your favorite ride ten times in a day if you want - there's no one with you to say 'not again'. No hanging out or amusing yourself while those with you ride something you don't want to ride, or lose out on something because no one else wants to do it.
3. You decide the times for each day. Feel free to stay in park until a 1:00am closing or go to a 7:00am opening - no one else to wait for that sleeps in or that wants to hit bed early. Personally I like to maximize my time in the parks. I don't get there at the crack of dawn(usually 9 or 10), but I'll stay until the last park closes. During a busy season, that can mean 2 or 3 am for extra magic hours. I might bounce between a few parks in one day, with some pool time tossed in, and manage to catch fireworks at multiple parks.
4. I stay at Wilderness Lodge. The great thing there compared to other resorts is that it's not spread out. At other resorts there a numerous buildings and I don't think it feels as homey. At the Lodge the lobby is inviting and always busy. You can sit in a chair and people watch or read a book. It's also a gorgeous building. It is a boat ride away from MK, which I can then connect to Epcot or some other resorts from there. Since the MK is usually the last one to close in a given night, it's an easy ride by boat straight back to the Lodge. The Lodge also has a nice pool - you can enjoy swimming or people watching as you relax by it. A nice pool bar there too. The pool area has a relaxing, charming feel to it. Plenty of water craft, bikes, etc, and walking trails. If you never stayed there, give it a whirl sometime, or visit it and walk around. Yes, it's one of the more expensive ones, but I think it's worth it, plus I think that also means it attracts a different clientel - no 'rif-raf' or obnoxious people, and there are kids but they're all well-behaved.
My first trip I stayed at the Contemporary and hated it - I thought it was too antiseptic - I felt like I was in a high priced Marriott(Tower) or Holiday Inn(Wing). For the same money I stay at Wilderness L.
5. Dining - do what you are comfortable with. Sit at tables or at the bar. Try one or the other and see what fits your fancy. Maybe try a restaurant you didn't before when you were with others.
6. Overall, the best thing about Disney is that it's all right there at your fingertips - entertainment, dining, hotel. It's probably the best place to solo. Unlike taking a vacation to a city somewhere, there's no need to go out and find things to do. It's all right in front of you.
GO AND ENJOY !