MonitLab doesn't merely monitor and alert you.
We keep the full check results for every check location and graph those results for you.
We collect and graph metrics for all check types, for which it makes sense to do it.
A picture helps a lot. You can make sense of problems and diagnose failures much easier by getting a visual. It's not a one or the other kind of thing either - we keep all check results (from all check locations) as well.