Integration/Functional/Acceptance tests are inherently difficult to maintain for a myriad of reasons: they take a long time to run, are hard to keep green consistently, can fail seemingly randomly, are cumbersome to debug, etc. etc. However, they can be priceless, if one manages to have a reliable non-unit test suite.
Is having such a suite, merely a pipe-dream? How are teams able to manage a consistently green, low maintenance non-unit test suite?