Jenkins- yours is an all too common problem, and I don't know how your city is set up, but generally, the medians (or esplanades or islands) are maintained by the public works dept. or the parks and recreation dept. Somewhere, there is someone who decides what plants get installed. People in this job either know what they are doing, or they don't.. Almost all cities have very limited budgets, and huge public demand for everything but plants. So the plants that are put there are proven but boring survivor-type bushes and trees. Many departments have Adopt-An-Esplanade programs that specifically give groups or individuals the right to plant what they want, with certain provisos, and absolving the munincipality of having to deal with it. In addition, many cities will pay for the water for a sprinkler system if you deed it over to them (which never made much sense to me, since everything that sits for an extended period of time on municipal property becomes theirs, anyway). If your city has no such program, go to the planning dept. and ask for one. Be prepared to hear a lot of "can't do it, won't work" responses, but keep going one level higher every time you get a negative response. Most folks that work for cities are, in my experience "the working retired", and they don't want to change the status quo.
I work for the city of Houston, Texas, a huge city with no zoning, if you can imagine that. My bosses have come to expect a degree of rebelliousness and hell-raising from me. This has worked to advantage with my neighborhood association, which has adopted several esplanades. It's a lot of work, but we have beautiful, organic landscapes now, which helps keep the $value of homes in our neighborhood up.
Best of wishes for your success!

I am sorry I didn't see your post sooner. Get a hold of the Project Green folks in Iowa City. They have been working with City Hall for over 20 years in developing the public plantings on boulevards, medians, prairie plantings at school yards. The Project Green Plant Sale/Garden Fair makes around 20-25k a year for projects and a garden tour which brings in 5-7k. Proceeds are used to purchase perennials, trees and and shrubs, soil amendments. They plant the materials and the city then maintains the plantings with a little maintenance like trimming done by volunteers. They put on classes with outstanding speakers for gardeners as well as Prairie Preview.

It is a great model for beautification and citizen managed green spaces, inspiring U City in Bloom and the Great Perennial Divide here in St. Louis.

Contacts: Anne Hesse,Mrs. Charles; Bernie Knight, Mrs. Calvin; Elaine Long, or Nancy Sieberling, Mrs. Frank. They can put you in touch or get you on the mailing list.

With that model in your back yard, you cant fail! Good luck and tell them I said hi! G