If any double flowers do develop they will occur late in the season rather than early. One of my favorites is a climbing rose with a summer blooming variety roaming through it. Clematis are not a heavy strangling vine. They grow through their host doing very little damage. If planting against a wall, your trellis should be constructed in such a way that it can be let down in one piece at house painting time.
Most varieties perform well in full or filtered sun.
Although clematis prefer four or more hours of good light each day, they will grow in most locations, including a bright north wall. The pastel colored hybrids have more intense blooms if grown in one of your shadier locations.