You are not going to have good results reducing the tree in size to any significant degree nor would the tree appreciate that sort of heavy pruning attention. So your choices are to leave in place, carefully thinning out or selectively pruning out a branch or two. But this will continue to impact the viewing of that face of the house and its windows. Or you could pay to have it dug up and relocated ($$$). Or you can just chop it down and replace with something that stays in a smaller scale.

People would pay good money to buy that. Some japanese maples of that size are sold at nurseries for thousands of dollar.

I have seen japanese maples with bigger trunks than that one turned into bonsai.

Would it be possible to cut half the tree and graft a weepin scion onto it so it never reaches a big height?

It is a beautiful tree and perfectly scaled for that space IF you can artfully prune the dense top. I could do it myself, but if you can't, hire someone. It will be cheap compared to removing and replacing it -- and a much more attractive outcome. If you are itching to move something, how about bringing that boxwood out from against the wall?

I think it's perfect where it is, it adds character to your home.

" If it were mine, I'd get rid of the boxwood and plant something else that would better compliment the Japanese maple."

Yes, that little ball has to go- it relates to nothing..

I'd put "All Gold" Hakone grass underneath that tree- I've got some under a deep red JM and it really pops..

^^^ I love the contrasting colors.

When I googled the grass you suggested, I found this wonderful landscaping image with so many interesting colors and textures. I think this would look great underneath that beautiful Japanese maple.

Credit going to Karl Gercens. There are so many gorgeous landscaping images in his flicker photostream.

I pruned it last night, took a couple of hours. Still could do more but it looks much better (it's hard to reach the higher branches). What kind of ladder do you use to trim something like this? I have an 8' stepladder but can't reach the middle/highest areas. Any other recommended cuts based on photo, let me know.

About the green meatballs (boxwoods) - my whole landscaping is being changed in about a week. That is why I posted - the JM was slated to go (replaced by miss kim lilac but I can't bring myself to like that). In that area underneath the tree will be huechera, coreopsis, hydrangea. New landscape lighting/wiring. I don't know if what is planned will "relate" to the JM though. The whole area will be much more filled in with plants and rock mulch replaced with hardwood mulch. I will ask my landscaper about the Hokone grass. He is already being driven crazy by me as I've changed my mind about things a gazillion times.

Just a word of caution about the new landscaping. Japanese maples really dislike any disturbance in their root zone and actually, any cultivation in that area can lead to rather serious root and disease issues and even death. Typically, the suggestion is to underplant at the same the tree is being planted and then just leave it alone :-)

If you intend to underplant now, you want to keep any cultivation/root disturbance to a minimum. So avoid any deep planting holes, larger plants, any perennials that require frequent division or annuals that need to be replaced seasonally. A shallow rooted, low growing spreading groundcover would be your best bet.

The shade garden photo is lovely but that type of planting is difficult to plant and establish now with a mature tree in place without risking serious damage to the tree.

" Would huechera and coreopsis qualify?"

No, neither are considered groundcovers, just clump forming perennials. The grass could work, as it is rhizomatous in its growth habit but will take a long time to fill in and is really better suited for shade.

I'd consider ajuga, Veronica peduncularis 'Georgia Blue', epimediums or hardy geraniums (cranesbill). All are shallow rooted, will spread to fill over time but not be too aggressive and can take both sun and shade or a mix.