If your driveway leads to a grand house on expansive grounds, the formal landscape is a complementary option. The "U" will likely be about two lanes wide and can accommodate a line of pyramidal cypresses, flowering cherries or a combination of similar trees in matched procession along both sides. Alternatively, line the outside of the drive with the cypresses and the inside with lower-growing box hedges or rose bushes. Fill the center of the "U" with geometrically designed herb gardens, or leave it as a wide lawn area dotted with sculptures.
For smaller houses with a one-lane driveway, place a focus tree in the center of the "U," surrounded by a ground cover of vinca minor or creeping thyme. Good choices would be a pink dogwood or double-flowering cherry for spring blossoms, a sugar maple for fall colors, or most types of fruiting or nut trees. These will also give shade to the front of the driveway. Another option is to create a berm, or raised area in the center, and place a group of trees such as a dwarf mountain hemlock with a Japanese maple and a clumping bamboo. Line the driveway on both sides with beds of bulbs and annuals such as daffodils and pansies.
Arrange a rainbow of wide flower beds within the "U" and line the outer part with a low hedge. Place taller perennials such as blue delphinium at the innermost curve of the "U" and plant subsequent arching rows of foxglove, daylilies, columbine, Shasta daisies, lavender, poppies and others as desired. An alternate design would be to create an edible garden. For example, line the "U" with blueberry bushes and fill the center with a strawberry patch.
Add touches to further beautify the driveway area. Among the most welcoming designs is the centrally placed fountain. These can be bubble fountains, or one that sprays into a small U-shaped pond. Other fountains have multiple tiers or large pedestals. Size the fountain so it doesn't overwhelm the "U." If a fountain seems too large for your driveway, a birdbath or appealing statue can suffice. Surround the garden ornaments with the plants noted previously.