Brian,
You might look at the Berkeley Physics Laboratory manuals. They had
a nice series of microwave experiments in Vol. B or C. I used several of
their experiments using X-band (3 cm) microwaves with good results. Their
experiment to measure the wavelength was essentially a Fabry-Perot
technique with two pieces of aluminum sheet with a carefully-cut, but
simple grid cut in them to make them partially reflecting.
My favorite part of the experiment used two very large wax prisms
which were used to demonstrate and measure the phenomenon of frustrated
total internal reflection. I love doing optics experiments at 3-cm
wavelengths; accurate placement of the components means getting them within
a few millimeters of the desired location.