Is it safe to just lay plywood over my attic insulation and wiring?

You need to figure out if your attic is framed with trusses or traditional rafters before you buy a single sheet of plywood. Most modern trusses are engineered specifically to hold the weight of the roof and the ceiling below, but they aren't meant for heavy storage. If you see 2x4s acting as your floor joists, they’re likely only rated for dead loads like drywall and maybe a technician walking around. Loading them up with heavy bins could lead to sagging or even cracks in the kitchen ceiling downstairs. Regarding those recessed lights and wires, you definitely shouldn't just screw plywood directly to the joists. If you compress the insulation, you're basically throwing away its efficiency. Insulation works by trapping air; once you flatten it, you’ll start seeing higher energy bills. The best way to handle this is to build a **sub-frame** or use attic stilts to raise the floor. This creates a cavity for the wiring and those light housings so they aren't getting smothered or pinched. Even if your light housings are IC-rated, they still generate heat. Giving them a few inches of clearance under the new floor is much safer than burying them. And those white Romex cables hanging around are a major concern. If you pinch one under a plywood sheet, it's a fire hazard. Raising the floor allows you to route those cables safely underneath without any risk of them getting nicked by a screw or crushed by the weight of your suitcases. One last thing: use screws instead of nails for the decking. If you ever have a leak or need to upgrade the kitchen wiring later, you can just back the screws out. Trying to pry up nailed-down plywood in a cramped attic is a nightmare and usually ends with a foot going through the drywall. Just keep in mind that attics have massive temperature swings, so skip storing anything sensitive like photos or electronics up there.

Have you ruled out moisture trapping before you seal everthing up? Even if you build a sub-frame, putting plywood over insulation can sometimes create a vapor barrier you didn't intend. If there’s any air leaking from the kitchen thru those light housings, you might end up with condensation and mold on the underside of the wood.

Also, have you checked if any of those coiled cables are actualy for your HVAC or fans? If you floor over them, you’re basially making it impossible for a tech to service anything without ripping the whole floor up later. Might be more of a headache than it's worth for a few suitcases.

I'm honestly a bit overwhelmed already—I didn't even know there was a difference between trusses and rafters! I just thougt they were all just 'the wood parts.' Is there a simple way for a total newbie to tell them apart without hiring someone to come look? Also, the sub-frame idea sounds smart for the wires, but won't that eat up alot of the standing room? I'm worried that by the time I raise the floor enough to clear the lights and the insulation, I'll be crawling on my hands and knees just to reach my suitcases.

I'm with the others on building that sub-frame; it's the only way to keep your insulation from getting crushed. One tiny thing to add: make sure you leave a small gap, like 1/8 or 1/4 inch, between the plywood sheets. Since attics have such wild temprature and humidity swings, the wood is going to expand and contract like crazy. If you jam them togehter tight, they’ll eventually buckle and pop your screws. Plus, those gaps acutally help a bit with the airflow issues mentioned earlier so you don't trap quite as much heat.