When I made the 'final' switch from film to digital several years ago, here's the procedure I went through with all my slides and negatives (more than 50,000 frames in total):

1. Digitized every single slide and negative at the highest level of quality available at the time. My intention from the start was to hopefully never to have to break into the physical packaging ever again.
2. Put all the slides and negatives in polyester sleeves
3. Tagged and labeled everything into a spreadsheet on the off-chance I'd need to find a negative (or a session) again I wouldn't have to go through every single negative looking for the one I needed.
4. Taped the sleeves onto archival quality (acid free) cardboard backing
5. Put the polyester sleeves + a silica pack into an archival grade vacuum seal bag (polypropylene) and used an industrial vacuum sealer to suck all the air out of each package (the cardboard was essentially in there so that the package wouldn't lose it's shape with the vacuum and crush my negatives).
6. The sealed packages were then placed in archival grade boxes, more silica packs were added to each box, I sealed each box with tape, and the boxes were put in a safety deposit box at a bank in my town with a reputation for keeping the ambient temperature and humidity at a rock-solid 55 degrees/50% humidity.

Overkill? Probably. Expensive? Definitely. Time consuming? It took nearly 6 months (I probably could have done it faster with some concentrated effort, but it was an 'assemble them while I sit in front of the TV during the down-times' activity)

My kids will probably simply throw them all out after I'm dead... It's not like I've got a bunch of 'undiscovered shots of JFK and Marylin Monroe' floating around in there... But I'm a worry-wart, and I just didn't want to keep myself up nights 'listening to my negatives turn to dust,' so I went for the 'nuclear option' of archival... Or at least as close to a 'nuclear option' as I could imagine at the time. I still occasionally think that it might have been better if I also vacuum sealed the boxes too... But I'm probably just being paranoid. :-)