I must be a weirdo (well, my husband would definitely agree with that.)
I find decreases much harder to do when I knit on needles larger than the yarn calls for. But, you make good points--a lot of times lacy patterns are done on bigger needles. What I posted is based on general guidelines, but they are definitely that-guidelines.
But I have been fiddling around with something that you might want to give a try (it may actually make it more difficult--this is just a suggestion. Also, I'm sure I'm knot the first person to come up with this.
When you get to the point where you need to k3tog, get a small crochet hook, and insert it Knitwise through the three stitches starting with the farthest left of the three stitches.
Grab your working yarn with the crochet hook and pull it through, thus making three stitches into one.
Slide the new stitch onto your right needle.