I had my collection in a storage locker for about 6 years. I had everything in lined, sealed plastic stackable containers, with silica gel. The storage venue was vermin protected. When my son finished school, he started university and got a place and my wife convinced me to move everything out of storage and into my son's place to save money. So currently everything stored in one room in my son's place. My collection, when I took it out, was in perfect condition, no damage, it was like I put it in there just the day before. This house is small and rest of my family suddenly back in Australia, so right now I am debating whether to try to build safe storage room in an existing garage or put it all back into storage. Sometimes I wish I had a different career, so I could live back here, but really hard to change as you get older.

Some updates.

Insurance:

I went with Collectables Insurance Services as opposed to American Collectors Insurance.  The latter would not cover M:tG cards or some of the other ephemeral stuff in my collection.  CIS also attached a rider that covers me up to the full dollar amount, passed $100k.  Of course, subject to valuation if I ever have to make a claim.  Also not covered for any type of flooding for this area.  So basically, fire and burglary, which is fine and about what I was looking for.

Packing:

I started with form fitting Sterilite containers and quickly realized how much of pain that would be.  So this is what I've settled on.  A small Bankers Box or BCW magazine box nested inside an 54qt. Sterilite gasket sealed box.  Line the gasket box with bubble wrap, bubbles down, to minimize shifting of the Bankers/BCW box.  Pack books and boxes into that.  Label, insert gel-packs, seal.  This will still be pricey, but should cover everything against bugs, leaks, and humidity.  Should also mitigate (i hope) any potential damage when I move them from the house to storage and then eventually back to the house.  While my use case is extensive, if you want to store some of your more valuable books and boxes longer term in closet or something this should do the trick.

When I packed for long what I thought was going to be long term storage, turned out to only be 18 months, I individually wrapped books in cellophane (saran wrap) and stacked the them all into cardboard boxes with half a dozen of those little desiccant pouches you can buy. The storage was a locker in one of these rented storage warehouses (Safestore here in the UK) so I didn't need to worry about moisture too much (only if I'd sealed any in) cos here in Scotland these things are pretty cold all year round. Just concrete and steel. Everything seems to have survived just fine.

Just my experience with storage. I'd imagine location temperature and humidity will always be the major factors when considering packing. But the little desiccant packs are well worth in IMO.