Low maintenance as in low water usage or perennials that requires little pruning/triming/weeding?
Perennials tend to require less maintenance than annual. Succulents & rock garden perennials tend require less maintenance than the average pants, and the least maintenance IMHO are acidic varieties such as azalea/rhododendron/heather (winter varieties).
Winter heathers may grow to 12" in height that make great border or filler plants, hardy and have very long lasting flowers (some varieties flowers up to 3 months in a season, doesn't lose leaves, stay away from summer varieties due to high maintenance and un-interesting flowers)
Azalea can grow up to 2'-3' tall with incredible floral displace (however it lose leaves in the winter).
Rhododendron flowers are similar to azalea, but the flowers are much larger and can be as tall as 8'-10', and do not lose leaves in the winter (dwarf varieties are 1'-4' tall)