well, i've only been collecting for little more 
than 2 years now, but i have my cels in both 
itoya cel books (which you can get at their 
website, on eBay, or through various cel 
websites) and in craft scrap books, and neither 
seem to present a problem. to ensure that they 
don't get scratched by the plastic, though, i'd 
put all of your cels in cel bags. hope that helps,

haruna