Hi, I just read your post. Don't know how far along you are in the "design" process, but I thought I would throw my 2 cents in (if it's worth that much! lol).
You mention a lot of rocks, but don't say whether you have a lot of soil. If you have some deep soil (with lots of rocks in it) then you may have more options for growing different types of plants. If there is just a thin layer of soil over rocky substrate, then your choices of plant matter will be much more limited. Based on the size of the area and your budget, you probably have a multi year project ahead of you. That's ok though, because as you progress, you will get lots of experience and lots of new ideas and will probably end up with something even better than if you could wave your magic wand and make it happen immediately.
The #1 thing I would try to do is get a hold of a lot of compost. Our property is for the most part unlandscaped and unirrigated. We brought in truckloads of compost to put around the fruit trees and the veggie garden. It sat in huge piles in a number of places in the lawn. When we finally finished moving the compost and raking the areas where it sat for so long, most of the vegetation underneath appeared to be dead. But low and behold, the bermuda (which is scantly scattered throughout the yard) came back and, unfortunately some Dallas grass as well. But what was amazing is how these portions of the lawn have done this summer without any supplemental water. This grass is thick and green and there are no cracks in the clay - and these are the only places in my yard where this is true. So, based on this "experiment", I would say that spreading an inch or so of compost over existing soil may greatly improve the fertility and the ability to retain moisture.
Second thought is to start to create some landscaped areas, meaning areas that you will not mow. Since you want to reduce the chore of mowing, think about the shapes you create to make sure you are not creating more "things" to mow around which will expand your mowing chore. You can work out from the house or in from the corners or some such idea. Personally, I would chose spots that I could easily view from the house or porch, so that I could maximize enjoyment of the fruits of my labors.
I second the idea of using native plants, especially those that are native your part of Texas and those that are used to low water situations. There is a really great book that I have used extensively in my landscaping efforts. It's called "Native Texas Plants", written by Sally and Richard Wasowski. This is where I learned 90% of what I know about native plants. Read through it and see what plants appeal to you. Look for those that will grow in your region and like soil and weather conditions similar to yours. Then start looking for the plants. Some of the plants are not available from garden centers, but I found many of them. Another option is to join a local chapter of the native plant society and see if some of the members will share cuttings. Most are generous. Plant swaps (check for these on Gardening in Texas section of GardenWeb) are another good option.
You have the option to select plants that will be attractive to wildlife such as birds (including hummers) and butterflies. A lot of the garden centes have lists of plants that will attract butterflies and hummers. You can glean some of this information from the Native Texas Plant book as well.
One note on native plants. Although they are much better at surviving our weather conditions than many non-natives and form significant root structures that help them make it through droughts, they will likely need some watering the first season or you will not have a lot of success. You can minimize their difficulty by planting them in the fall (with some supplemental water), giving them the entire fall, winter, spring to become established and build their root structure. If you plant in the spring, you will probably have better luck with small plants. Also, once established, even though many will survive no watering, expect to lose some and realize that without supplemental watering, you will get shorter flowering periods and less growth than if they were given the extra water.
I find heavy mulch to be rather indispensable. It will help your plantings retain moisture and keeping maintenance down. Personally, I think if you don't mulch, you are wasting your time. While I greatly enjoy gardening, I don't get much enjoyment out of weeding nor do I enjoy dragging hoses and sprinklers around. In my book, mulching is a necessary "finishing touch".
Ok, I've babbled on enough. Hope these thoughts are of some use. Good luck!