My kids graduated from going door-to-door to scaring the crap out of those who were, and they said that beats going door-to-door. Less walking, and you still get to munch out on candy, which is why I have to buy so many extra bags. My oldest son invested in a Michael Myers outfit, and my youngest son made an awesome scarecrow outfit that he wears, and every year for the past eight years they've been laying out new and devious ways to scare people when they come to the door.
The first year, Sean (Myers) would just open the door. The next year he was hiding in a hallway window that people would walk past to get to the door and scare them from behind. Then he found a good hiding spot to come in behind them, and gradually escalated to fog machines, strobe lights, and lots of other fun stuff. We ended up having the most popular house on the street and lots of kids that walked by were talking about how that was Michael Myer's house.
About, eh, middle school time, our whole town just sort of stopped doing Halloween stuff. Fewer houses, fewer trick or treaters, nothing to do. So I started haunting by dressing in costume and handing out candy.
Let's say it's grown exponentially from there, and Halloween is coming back. We started drawing a crowd, the guys at the Mortuary in the next block started haunting, and the last 5 years the town has done TOT on main street (conveniently a block away).
Don't lose the spirit. Find a way to make it fun for yourself, and others will find you. And I have plenty of adults who show up at our home haunt just to see what we've done, because they appreciate it. Get a good costume/mask, put up some lights, get the old cheesy indoor nostalgic decorations out of the attic. Start slow, it'll come to you. If you've got neighbors, you've got an audience.
I think the important thing here is every one of us have made this transition. All of us started out as trick-or-treaters, and eventually "got too old" to be doing that, and moved on. A lot folks migrated to throwing/attending Halloween parties and the a lot of others migrated to being the candy giver rather than the receiver. I've never been big on giving or going to parties because they are a one-night-only kinda thing, and if I'm going to expend a lot of effort, time, and money on something, I want something that'll last a few weeks or a month.
I started throwing parties to enjoy the holiday and have also started dressing up for ToTs. I decorate our house/yard because I enjoy it and each year look forward to adding new stuff. I had several parents last year say that they love coming to see the decorations each year and that I don't make it too scary for the real little ones (we live on a street that had almost all elderly people here when we first moved in and now it's starting to switch over to young families...... Very few ToT and decorations. I like to think out house encouraged people to decorate because each year more and more people are decorating.)