Also, when increasing the ABV, you will probably have to adjust the hops upward to counteract the increased maltiness or sweetness.
It isn't the amount of alcohol in a beer that makes it great. It's the taste. If you up the ABV to the point of a cloying sweetness, you probably won't like the taste.
I'm learning that balance between malt and sweet is very important in the overall flavor of a beer. Some are best when towards the malty side. Some are best when towards the hoppy side. Some are best when they are balanced between malty and hoppy.