You've answered virtually all your own questions :-)

I would choose one side of the 'Y' and cut it off now....you won't even notice the difference in 2-3 years.

As for a heavy pruning to keep it small....not a chance. Silver Maples will send out shoots 6' long in one season in response to a heavy pruning.

As for other trees, choose your size and desired attributes, & I'm sure lots of suggestions will pop up.

Is already throwing bed out of balance visually, should be in center - or bed should be re-shaped (or removed and replaced in a different spot, as where it is now with the shape it has it is taking a bite out of the lawn which does not produce a pleasing effect - when your lawn no longer has sharp corners then you know your beds shapes are getting to where they should be - if you want a relaxed and gracious appearance). Later it will overwhelm the other plants and become too large for the size of the bed.

Notice the booklet at the bottom left of the page, possibly that would be of interest.

Here is a link that might be useful: UNH Cooperative Extension - Family, Home and Garden Education Center

Most definately a Silver Maple. I actually love them--in the right place. I have four or so in a mixed stand grove I planted on 1.25 acres or so.

If allowed to grow there, it will run into the other trees you have there. You may not care and like the canopies to merge. That is what I have done.

A big problem is that low crotch which you know how to take care of. It will not even be noticeable that you took care of that in 2 years or so.

And, the biggest problem is that septic system. How close is that? I would not put a silver maple within 100' of my septic system. I have removed red maples and a white alder that were too close. I wouldn't even think of letting one of my silvers close.

Thanks for the replies. I was thinking to buy that book (I've read most of what the UNH extension has online) already, and I probably will. Unfortunately, I think what I really need is some intro to landscape design ;(

I agree that the location of the tree in the bed is odd, and well, the bed itself isn't the most aesthetic shape. I put this in when I built the retaining wall, in order to not have it all boring lawn. Maybe I'll see if I can get some better picture this weekend and see if I can get some design help here ;) The septic doesn't make it any easier, and I don't even know exactly where it's at. Definitely too close for a large tree (20 ft to the edge would be my guess, certainly not 100).

So is the tree really going to straighten itself out if I cut one half off? The crotch angle is wider than it may look in the picture. That may be all academic, but I guess I might keep it for a couple of years while growing some replacement.

I'm thinking an upright Japanese Maple might be a nice center piece there, how about a Seiryu? I just ordered one, but it'll be years until it has any kind of size.

I don't think even a silver maple will compete with most of the other trees there any time soon, though, there are many really tall pine trees there (which are left from what I guess basically used to be a forest, and so they're not particularly pretty, having only green near the very top. But that's another subject... (though actually related to the whole "where do I want my landscape to go" thing)

I'm frequently suggesting GARDEN DESIGN ILLUSTRATED by John and Carol Grant here, and for good reason. Reprinted many times, unique inexpensive classic. Half Price Books near me has had copies for less than 10 bucks several times that I know of. Looks like your layout has a bit of the bold flowing lines they talk about.

Japanese maples, trident maple, shantung maple to name a few would be much more suitable tree than silver maple. Nicer looking and not so aggressive root system like silver maple.

Any large-growing maple will become dominating over time, making them comparatively hard to garden under. You do appear, however, to have lots of room.

Japanese, trident etc. maples are small-growing and therefore easier to work with.

Kaig, What a great place for an ornamental tree. Dont let that tree ruin all the time, money, and effort that went into that wall!Looks like your location and conditions provide many,many great possibilities. Give that one to the neighbors !! HI HO SILVER.....AWAY!!!!!

Paperbark maple would be excellent tree too.