I'm a master gardener and hate lawn care, so I reduced the amount of grass by expanding my perennial beds. Now that I've been doing it for over 10 years, I'm less interested in weeding and maintaining and collecting the latest-and-greatest plant.
So, after much research, I've come to the conclusion that the easiest-to-maintain landscaping is a well-designed group of shrubs. They are more work to install, as you need to do supplemental watering for 2-3 years (less watering in the second and third years, but you still need to help them along), and will require some weeding in the initial years if you start with smaller plants, but after that, they only require a little pruning (once or twice a year) to keep them looking nice.
Of course, a well-designed shrubbery includes plants that look after themselves and don't outgrow their space. Thus, they don't need much pruning. Or, if they will get larger than the space, you can keep them under control by cutting them to the ground every decade or so. (Many—not all—older hedge plants do well with this method.)
So, I'd consider doing what you can to lessen the task of mowing. Perhaps planting shrubs in the steeply-sloped area would cut the mowing time in half (not to mention making it less dangerous).
An excellent book is Designing Your Gardens and Landscapes by Janet Macunovich. She explains how to evaluate your site (crucial if you want to lower your maintenance), choose your goals, plan for maintenance, set your budget, etc.
But really, the best thing you can do is get educated. I like the YouTube idea, but check out your public library, too. I've found that the information I find on the internet about gardens/landscapes is generally not very good quality, especially when it comes to learning the basics. Books and other paid content are much better.
You should also check your state's Extension office. They will have a lot of information that is specific to your location. (Assuming you are in the USA, of course.) You can also look at neighboring states, too. I've found that some states seem to specialize in specific areas—despite the fact that they're all supposed to be supporting community education.
http://www.csrees.usda.gov/Extension/Good luck!
