Well, I'm a huge fan of American hornbeam (Carpinus caroliniana), but it will get somewhat bigger than your specifications. I agree totally about nothing formal or too rounded (can't stand that look).
What about rhododendron? Maybe you could shape it for a more tree-like look? Then there's sweetshrub (Calyanthus florida) and spicebush (Lindera benzoin), both excellent native shrubs. Spicebush has small yellow flowers in spring and bright red berries later for the birds. Sweetshrub has maroon flowers that smell wonderful -just like strawberries.

I usually only recommend natives.

PS- (I can't help myself...) Love the username. So, how many roads must a man walk down? ;-D

One of my favorites: Cornus officinalis

Looks like Klehm's Song Sparrow has a cultivar for sale & forestfarm has 2-3' tube-seedlings.

Dax

Sweetshrub (Calyanthus florida) - Would it train well into a tree form? I've looked at it before, but was always scared off by the suckering tendency. Because I'm on the cooler end of zone tolerance, would it stay smaller for me?

Spicebush (Lindera benzoin) - Interested in this one as well. Same question - - Would it train well into a tree form? What's the story on the berries? Do they fall or persist? Will birds eat them?

Acer - So, how many roads must a man walk down?

You multiply six by nine of course! :)

I don't think sweetshrub is what you want. I have one (@ 8 yrs old) in a partly shady spot, and it is kind of floppy and suckering like mad, which is fine for me, but may get in your way. It also isn't very tall - maybe 5 1/2 feet, max, and more than that wide. Great flowers, awesome fall color, but not, I think, what you're looking for.

Except for the Crimson Queen, the other Japanese maples will get far too tall for you. There are some other, more dwarf forms you could consider that will stay closer to your desired height.

It seems you may have a desire for red foliage? If so, I'd consider one of the ninebarks (Physocarpus) like Diabolo, Summer Wine or Center Glow. These are relatively easily trained as a standard and will stay at height (or close to). When trained into a tree form, these really display the exfoliating bark the shrub is known for. Another possibilty is Sambucus Black Lace. And hydrangea "trees" make excellent small ornamentals. These are cultivars of H. paniculata trained as a standard - easy to find and very popular.

gardengal48 - The Ninebarks are great but I already have one on a standard in another part of my yard, so wanted to do something a bit different. Hydrangea would work as well. I used to be very anti-hydrangea, but as of late have softened, but still have to check everything else out first.

Gardengal48 brings up a good point that I don't have hard facts on yet. I've been told that Japanese Maples will not get to predicted size in our zone and grow very slow here as opposed to warmer areas. Is this true or a garden legend?

Thanks for the heads-up on the sweetshrub. That's what I was worried about.

Colder winter temperatures could conceivably slow growth but there is no botanical reason the trees should not attain their mature size (and remember that tree size info is generally provided as a range rather than a flat footage). Soils, water and length of growing season is likely to be of greater influence. One of the limiting factors in colder climates is damage caused by snow and ice accumulation as well as late freezes that may affect budding/leafing. These can affect overall growth simply through breakage or dieback.

Are there any of the smaller Japanese Maples you could recommend?

Definitely other Acers and also hardy!

Acer palmatum 'Skeeter's Broom' (witches broom of 'Bloodgood' so hardy to zone 5), 'Callico' is another, less-hardy, better for 5b-6a.

Dax

I've attached a nice listing of dwarf forms. I'd do additional research on mature sizes, however......the heights quoted in this link are in general about 33% on the low side.

Here is a link that might be useful: dwarf Japanese maples

Anti-hydrangea? Hydrangea paniculata is arguably the queen of all shrubs!

Where are you in WI? Most Acer palmatum don't do well in WI 5B. Acer shirasawanum will do better just because it leaves out later. I'd suggest you begin there otherwise there are "certain" A. plamatum cultivars that do well. Crimson Queen and Red Dragon are two of those cultivars.

I asked one of the master horticulturists at the Chicago Botanic Gardens why they don't have any Japanese Maples and he simply said they don't do well because of the dry winter winds so they just don't plant any. However I know many people in that are that are successfully growing JMs. Their 5B is much different than our 5B in SE WI.

"Anti-hydrangea? Hydrangea paniculata is arguably the queen of all shrubs!"

It is a weird childhood association. There was a scary house covered in them near where I grew up, so, hydrangeas = creepy. I have the opposite association with lilacs. Wonderful childhood memories.

I am currently in a hydrangea recovery program and have a Limelight and an Oakleaf. One day at a time. :) I do realize that a hydrangea on a standard is probably the easiest and most accessible way to go for this spot.