Safest spot to get a landed successfully for a vehicle is between the hangars on VBase - anywhere else on concrete is ok too though (regardless damage and enemy proximity).
You can land vehicles at the spawn points (yellow arrows on map), but there you have to be careful that you have no damage and there are no enemy vehicles in the proximity (im not sure on the range here).
On Airfields, landing on concrete will be successful. For ports its a little harder to judge, since you get a successful landings on some parts of the grass. Best bet would be to just make a few tests in OFFLINE or the TA if you want to be sure.