You're a fool to have a spreadsheet. It can be used against you in divorce court.
I use google sheets so I can edit it on my phone in addition to computer. And it's hosted by google via the internet so if anything should happen to my computer it's still there.
I have the spreadsheet separated into two sections: modern and older (everything pre-90's era). Those are then separated into columns: Brand & Item #; Item; Date and place of purchase; What i paid; and notes. I have the individual items in alphabetical order with the exception of pre and postwar which is in numerical order. Accessories, track, power, and any railroadiana is in a separate sheet.