i have 2 small children (6.5 & 2.5) in the house and a wife who had never touched a gun before she met me so this is a constant issue. I use a gunvault that is bolted onto my night stand that has a Glock 21 on the top shelf with an Itac WLL1 light/laser combo. The bottom shelf is extra 21 mags and loaded AR Mags. I have an unloaded AR under the bed in a little sling that I made. It's actually up under the fabric on the bottom of the box spring, highly unlikely you'd find it if you didn't know it was there but I can have it out in under 5 seconds when laying flat in the bed (I've practiced and timed it quite a bit). In my closet which isn't the walk-in but a regular reach in closet I cut out the drywall above the door opening and made a compartment that holds a 18" barrel shotgun. I made a door out of 1/4" thick plywood and put a piano hinge along the top. I painted it to match the closet walls and if you didn't know what you were looking for you'd never see it although you can reach up and bring out the shotgun pretty quickly. I keep it loaded but not chambered and do have the door set up to add a small lock if I ever feel the need.
I have another gunvault, the small biometric model that is mounted to the shelf in the living room where I keep my wallet, knives, flashlights and everything else that leaves the house in my pockets. It easily holds my primary carry gun and my back up when I come home. At the front door I installed one of the small in the wall safes that mounts between the studs it's a combination lock but I recently purchased a biometric lock to upgrade it but haven't installed it yet. I built a small shelving unit that holds keys and cell phones etc. with chargers built in. I mounted this over the safe with a hinge on one side. You'd never notice that it even opens if you looked right at it.
Everything else lives in my large Liberty Safe in my wife's walk-in closet. I feel like I've kept my kids safe while maintaining pretty easy access in every part of the house. My son has who's almost 7 has just started to really become interested in shooting. He's been shooting my M&P 22 pretty well and wants his first "real" AR for his 7th birthday. As a side note even when I'm home and have locked up my primary carry gun and my backup since I bought my LCP I almost always have it in my pocket until I go to bed. Even laying on the couch in a pair of shorts I hardly notice it's there. I was always taught the best gun was the one you could get to the fastest.
As far as a place for long guns my dad built a cabinet into the wall between the studs and made a solid wood door with heavy hinges. He installed a regular combination home entry door lock exactly like he has on his house doors. It's not as secure as a gunsafe but most burglars won't take the time to get into it and it keeps the grandkids out. It holds 2 long guns and has a shelf above for handguns, ammo, flashlights etc.