What can I grow in a road median?
Your criteria is salt tolerant, heat tolerant, deer resistant, ground cover, and low maintenance.
Along US Route 1 in Langhorne, the planting have been sucessful. I believe they are ornamental grasses and Lavendar and possibly some Lobelia. They satisfy your criteria somewhat, but the grasses may be too high for your sites. The plants are grown in cut outs in concrete and are maintained by residents in case you wish to get informantion from them. However, I would point out that these grasses may be too high for your sites. There are ornamental gasses that do not grow over a foot or two tall.
Juniperus horizontalis will work well as the main plant. The creeping juniper grows a foot or two high and and spreads 4 to 8 feet. It would require some pruning to keep in from growing over the curb. Bare spots could be filled in with a mulch, specimen plants or temporary ground cover like pachysandra procumbens. These are all natives and show vegetation year around. English Ivy may do better in full sun, but is not as deer resistant. Another low growing shrub that spreads is Rhus aromatica 'Gro Low'. They would add some color, but drop their leaves in winter. Vaccinium angustifolium, the Lowbush Blueberry, is another attractive plant, but may suffer deer damage on occasion. Red and yellow twig dogwoods could be planted as indvidual specimen plants that would not block vision greatly.
Two inches of mulch should keep the weeds down and cut down on maintenance. Using fresh wood chips is discouraged in beds since it depletes nitrogen, but might work well where you are discouraging weeds from growing. The mulch also will preserve moisture in the beds.