Generally, the surface installations with a tower in the icon allow landings, those without don't; the exception appears to be the Engineer bases.
If you look at the system map, landable planets and moons have a blue circle around them.
Tips for planetary landings
Set 50% throttle about 0.3 is away
Initially aim for the centre of the object, then pull up to about 45 degree descent.
Flatten out to 1km of the surface, choose landing site, drop gear and stop. Use thrusters for the last bit. Around 150 metres, you'll get the landing surface indication. Either land gently, or find a suitable site.