How about microprobes and balloons?
How about a series of microprobes with various instruments that could be scattered all over Mars? If a few get lost, it is unfortunate, but not fatal to the overall mission. Not like losing one large, expensive probe.
And whatever happened to the idea of a balloon that would drift for days across the planet's surface, landing at night to take samples of the area, then floating off to image the surface along the way?