I have papers my kids did in school 10 years ago and it is faded and yellow. I never use paper that is not archive safe. I put way too much work into my pages for that.
I buy Wausau Bright White at Office Depot - it comes 250 sheets to a pack and lasts a long time. It is acid free and lignen free and the only white I will use in my scrapbooks. It is heavier than copy paper but not as heavy as cardstock. I love it. Really bright and crisp.
I use a lot of brochures and airline tickets - I generally copy them on this paper (I have a good grade HP color scanner/printer).
If I'm using something on original paper which is not acid/lignen free or if I'm not sure - I scan and copy and print or just copy and print it on the Wausau Bright White.
If I used color paper for my journaling, it is always acid-lignen free. I often just cut a 12 x 12 to 8 1/2 x 11. lately I've had printed more of my journaling on different colors.
I also print on vellum - that has a nice effect!
Whenever I do use original papers in my scrapbooks that won't work to scan or copy, I always spray well with "Make it Acid Free".
I made a scrapbook when I was a teenager and was brokenhearted when we found it last year and everything was ruined. I also did my children's books through teenagers with non-acid free products and now they are to do over - they are in awful shape. I learned my lesson.
My scrapbooks are too important for me not to invest just a little more money to buy products that are safe.