I don't think the situation is as stark as you think it is. The large trees you have planted to either side of the driveway will eventually form a canopy over the drive that will compete with the driveway. Another quick fix might be to build a trellis for vines that extends over the garage doors, for something like Wisteria vines of Evergreen Clematis. It doesn't appear that there is enough room between the sets of garage doors to squeeze in a planter for something vertical between the doors, but this is a common trick used in monster California homes with a wall of garage doors. If cost is not an issue, (which in this economy, I doubt is the case), you could always reduce the visual impact of the concrete driveway by redoing a portion of it as bands with more decorative contrasting hardscape materials, or even use turfblock driveable paving suitable for growing grass to bridge the two sides of the driveway. This could also be done closer to the house to form a "lawn" within the "L" shape of your house, but wouldn't make much sense to do this if you typically leave parked cars on the driveway during the day.

I guess no one is going to be surprised that the tree screams out to me for limbing up. But now it's a predicament. The branching structure is such that limbing it up like it ought to be would disfigure it all the way to the top, because the major upper limbs begin very low on the trunk. (This should be a general reminder to people to pay attention to the branching structure while the tree is young and as it grows, and not think all the trimming work can be successfully done at the end. It can't.) Hard to tell exactly how close the tree is to the house, but its position (as well as its structure) is not flattering to the house. I'd consider removing it on account of that. If removal is not an option, then remove 4-6 lower limbs and improve it somewhat. Actually, trees off of the corners of the house would be much more useful and flattering. For the time being, I'll ignore the existing tree and go with a scheme more like this.

Bernik, the trees you've mentioned -- pine, sweetgum -- are positively huge so I can't imagine how they would fit in the small space for which you're considering them. For that spot, I would think you'd be looking for a shade tolerant large shrub, possibly multi-trunk, that you could limb up into a small tree form. Since you're trying to grow a lot of plants that require as much sunlight as possible, resist the temptation to add too much more shade. In order to determine where to fit a raised planter ... you might consider the back yard space to be more or less a room. The grass lawn is the central path/floor space and the plantings around the edge are roughly equivalent to furniture, cabinetry & appliances. The latter form a perimeter of sorts around the central grass path. If you need more "furniture/cabinetry/appliances," one option is to thicken the perimeter border and shrink the lawn/floor space. Then, you can squeeze more things into the border area. You don't want to squeeze the grass/floor area too much or make it too convoluted or it will become difficult to access the furniture/cabinetry/appliances area, or those things maybe become, or look, cluttered and messy. You need to develop a reasonable balance. It will be hard to maintain visual appeal if you make the lawn/floor too small and the border/furniture too large. The red line is an example of how you much shrink the lawn and enlarge the border. Since you will be the sole judge of how right or wrong it is, the degree of how much lawn-shrinking is acceptable weighs more on you than anyone else.

I am from Syracuse NY so I understand! Any dwarf conifer that is evergreen: slowmound mungo pine, miniature false cypress, dwarf japanese garden juniper, fire chief globe arborvitae, and some ornamental grasses, blue fescue. Best wishes! I can come to plant too :)!