So currently the laws are still pretty lax on store of Airsoft guns. There was a recent supreme court decision but it doesn't seem to have trickled down too much in regards to storing them similarly to a firearm.
The best advice I have for you:
1) Contact your local police department and ask them what they would deem as appropriate storage. Many will tell you there is nothing requiring them to be locked up but some may, so best to check with them first. Worst case scenario is if you get into trouble down the road, you can point to that email as proof that you did what you were told.
2) Consider your household and surroundings. Do you have children? Young siblings? Are your parents or family members okay with the presence of weapons? Are your neighbors aware of your sport? If you are going to store the weapons out in the open (on a gun rack, or a wall hanging for example) then make sure that they are not in reach of young ones, or in view of an open window. People do look in, and if they see an assault rifle hanging on the wall, expect a visit from the police sooner or later.
3) Treat them as if they were a real firearm. I have over twenty guns in my household hung up on walls, and the rule for all them is that they must be on safe, mag out, battery out and chamber cleared before storage. You wouldn't store a real gun when it was hot, so don't store an airsoft gun that's hot. Remember that when you have people over, they will often want to look / touch and almost always that involves pulling the trigger once. We've all seen that Youtube video of the kid shooting his monitor. Don't be that kid.
Finally, get creative. I've seen some awesome pieces for gun storage, from roll out closets to folding seat-racks. Figure out an idea you like and make it happen. It's your collection, so make sure you are happy with how they are stored.
Hope this helps!