GOCE is a wonderful (and beautiful) experiment. Its scientific contributions are particularly wonderful.

When I think of pretty gravity experiments, there are many, as the form must follow the function and gravity is geometry.

I'm particularly partial to the laser-ranging satellites:

https://en.wikipedia.org/wiki/LAGEOS

https://en.wikipedia.org/wiki/LARES_(satellite)

LARES is particularly cool, as it is (and may forever be) the densest object of its mass in the solar system. As so many gravity experiments go, systematic uncertainties are more-important than raw signal, though, so LARES 2 is composed of nickel instead of tungsten. It'll still be quite a day when LARES 1 re-enters; it'd be quite a sight to see.