Personally, I've had a few good ideas for meme maps outside of distorting other maps. I would list them here, but I have concern that those would be taken in next year's April Fools contest, for better or for worse. Regardless, I think I have a few ideas on how to help you create an original meme map.
Step 1: Brainstorming
First off, you gotta think outside the box. Don't just think brushes: think funcs and triggers. While I haven't made an actual meme map yet, the two ideas that occurred to me seemed like decent ideas that I hadn't seen used yet. I'd say the best way (in my opinion) to try and do something is to try not a force it: ease into a mindset where you aren't worrying too hard on how used the idea is. Once you have an idea, it's on to step 2 for you.
Step 2: Working Hard (or hardly working)
Now that you have even a fraction of an idea to work off from, you either need to base your map around that idea, or work your idea into your map naturally. Let's look at Trainsawlaser for example. When Crash originally made that map, he started with a pretty basic viaduct layout that he found enjoyable. After some time, he started working in trains, saws, fire, lasers, and tons of hazards all around the map for the gimmick to stick well; and let me tell you, it stuck well. However, that only goes into working it in after your map has been made. For working it in right off the bat, we'll look at Dog3, another meme map that has some recognition in the community. When Another Bad Pun worked on that map, I assume they started their map with the knowledge that it was going to use Minecraft textures and the gimmicks that play into the joke. Anyway, my point is that you should think well about how you will put your idea into the map itself.
Step 3: Trial and Error
If at first you don't succeed, try, try again. Sun Tzu said that*, and he knew a thing or two about war. When something goes wrong with your map or if you simply don't know where to go with it, don't be afraid of changing the idea. If there's anything I've learned from mapping, it's that you can't get too attached to something: if it has to go, it has to go. That isn't to say you can't rework things to get similar effect: all I'm saying is that if you can't do it with your current situation, sometimes it's easier to just remake it from scratch.
*Sun Tzu did not say that: it was William Edward Hickson
Anyway, I hope this helps you at all.