The OP asks " ... how should I go about doing this." Your property appears to be rather flat. Coupled with close neighbors, things can get sticky. Start by getting someone other than yourself to document the existing grades over all of the project area. Use an engineer, surveyor, LA, or one who has many years of experience. The result should be a contour map with spot elevations also shown. The most important thing is the location where water is crossing the tract boundary. Before starting the design, study the drainage law of your area. Law differs from state to state, but the most common applicaton is the civil law doctrine of drainage. Here I repeat what I said on another thread. Note that part in bold. A good overview can be found at: http://publicworks.co.marion.or.us/engineering/DevEng/drainagelaw.asp "The lower owner must accept water which naturally comes to his land from above, ..." In Arizona: https://www.coconino.az.gov/uploadedFiles/Public_Works/Homeowner_Guide_To_Drainage.pdf "A second drainage law is "The Civil Law Rule of Natural rainage". This rule states that a landowner has the burden of receiving onto his/her land the surface water naturally falling onto and freely flowing onto it from land above it. The rule further states that a landowner has the right to have the surface water falling upon his/her land and naturally flowing onto it to flow freely from it onto lower parcels as it would flow under natural conditions. The key words are "naturally flowing". Any modifications to the surface topography or the drainage ways that cause natural flow to enter or leave a property differently (different peak flow elevations, frequencies and flow locations) can create a liability and put you at risk regarding litigation." Or from: http://web.aces.uiuc.edu/vista/pdf_pubs/DRAINAGE98.PDF "A landowner has no right to obstruct the flow of surface water. The owner of lower land obviously has no right to build a dam, levee, or other artificial structure that will interfere with the drainage of higher land, according to the CIVIL LAW as it is applied in Illinois."

Don't know if this will help or not. Just wish I had an image to help make my point-it is just a memory in my head. Here is my memory: Up in the mountains east of the valley I live in I ran across a very cool site. It was part of a stream that was almost entirely a rock such as shale surface with veining and cracks in it that water flowed through. Here and there were sedges and other plants and even very small cattails (even though it was probably the normally large T. latifolia)l. There were scattered small pools of water here and there. It was way cool walking over this "bed" and checking out the little pools and plants in the cracks. As far as replicating it I really think that the amount of liner you have is just not enough when you take into consideration a small outflow pool and a small inflow pool. Ten feet just does not sound like enough to really work with. Perhaps only just a small pool for birds to bathe in might be a better use-make it shallow with a sand fill to make the pool shallow for birds and provide rocks stuck in the sand for perching. Best I can think of on the spur of this moment.

I don't have good luck with greggii either. That red one in the pics is darcyi, which is doing great with water just once a week when watering the new grass. I actually bought one from Flowers by the Sea to have in a pot and they are fairly brittle. That one on the berm is actually a piece I broke off and rooted and it's done that well from starting as a cutting this spring. I've never grown it before but it seems to do great in DFW. I amended that berm with some compost before I planted but that's it, aside from that it's nice black gumbo clay. Really hoping it overwinters but even if it doesn't I'll get another next spring.

I came across this photo that might provide some inspiration as you continue to landscape your dry creek bed. Even though yours doesn't meander you could provide the illusion of curves by alternating rocks and plantings along the edges instead of placing them evenly on the sides. By the way, love the photo of your hubby on the porch. He looks well pleased with the work as he should be :-) Here is a link that might be useful: