I am using a two blade easel that got for free, I bought a bunch of mats from an art place and was intending to use them the size of the mats are 11x14 with 7,5x9,5 opening so that gave a bad vibe about what is going on with my sizing, I can't get those measurements! I guess I will have to learn how to make my own mats because sometimes I could crop and get the image all the way to 8x10 but other times I had to cut half of an important part of the image. Thanks for the tips!
One of the thing I do is to print the full negative frame with some white space at the bottom. This gives you a spot to title it and sign it.
The other thing is printing the sprocket holes to fill some space.
See the examples.
Mark Barendt, Beaverton, OR
"We do not see things the way they are. We see things the way we are." Anaïs Nin
A four-blade easel gives you much more freedom to place the image where you want. As you've discovered, the 24x36 image doesn't fit well on most paper unless you do as mentioned above, crop or use an off-center image or make test strips first though I find this to be a pain.
There is sometimes unwanted empty space or objects on one side of the frame that lets me print to a full or near-full 8x10 but the rest of the time I just plan on matting it as I want. However this presumes you are cutting your own mats, otherwise you'll need to shoot and print "to order" as mentioned above.