The 3X ship/fleet training is quite a useful trick to use with dual-moon worlds. I normally play vaccuum breathers, and when I find one of those, I build a PSY, Ship Training, and Fleet Training on all three. Main planet also has Resupply depot, and is filled out with whatever else is useful. Moons are filled out with Cargo Facilities. I'll have somewhere between 5-25 BSYs in orbit and the planets have shield-heavy WPs (ie, 1xComputer;1xPDC;1xCSM;13xShield).
It's really nice when I find one where all three are Atmosphere: None.
As for all the others, I'll at least colonize them just for a single research facility. Or, if it's between warps or fairly close, a resupply depot.