I never really take off my designer's hat, and so I'm always seeing examples of good and not-so-good designs. Two of my favorite places to look for both are corporate campuses and public works: not only do they have to satisfy technical requirements far beyond anything I'll have to deal with in a home garden, they also have the budget to do it right (not perfect, just right). If one of these megaprojects is successful, I steal what ideas I can, to scale to the residential scope and budget. And if one is failing, I feel like I've struck gold - because I can learn from their expensive mistakes without spending a dime of my clients' money.
Prolonged rainy spells are great for pointing out problems in grading and drainage. Here's an example of what I consider a failure at the newly redesigned Caltrain station at California Avenue in Palo Alto: you can see the raised concrete planter has a drain outlet at its base. But where does that water have to go to drain away? Across a path (a wheelchair ramp, to be precise). This is, at best, an inconvenience for those of us whose shoes get wet walking through it. But at worst, it's a safety hazard no matter whether you're walking or wheeling. To compound the danger, this is below grade, where the perpetually cool and shady conditions encourage the growth of slippery algae on the wet concrete.
To my eye, all this risk could have been prevented by simply including a drain at the base of the wall, or perhaps tying in the wall outlet to the slot drain beneath the walk. Either would have been a relatively cheap solution compared to the potential costs of the problem. I hope we never find out.
When you're designing your landscape, remember: water will always find its way downhill. I'll let you know if the City decides to address that little fact here.