I have 3 sets of sheets for my bed (2 just isn't enough- I've had somebody vomit or pee on my bed RIGHT after I'd changed my sheets and before washing the second set!!) I have 2 sets of sheets for each of the twin beds- I don't change them all on the same day so I have extras in case of above mentioned emergencies. Besides, a child can always climb into my bed if her bed gets soiled. We have 2 blankets for each bed (except 3 thin cotton blankets for my bed, since I change them every time I change the sheets.) We have enough pillowcases for each change of sheets, plus 2-3 extras.
We have 3 towels for each family member, plus about a dozen washcloths and about a dozen hand towels (both get used for cleaning, in an effort to reduce paper towel usage.) We also have 4 tablecloths- 2 solid color with lace overlays (I guess we have 6 if you count the lace overlays as separate tablecloths) that we use for Shabbat and holidays, and 2 floral prints that we use for everyday.
We recently gave away/are about to give away a lot of linens. We simply don't have the storage space we used to have, and we have a tiny, convenient washing machine. I literally do 3-5 loads of laundry a day, so we don't need as much stuff. If you do laundry less often, you might need a little more.
Clothing: I have about 5 everyday outfits, and 3 fancy outfits. My son has way too many, but they all fit in his dresser drawer so I don't worry about it (and it's not really too many when you figure that he sometimes goes through 3 outfits in a day if he keeps spilling water on himself, or has an accident when he's not wearing training pants. The girls still have too many clothes, but we already gave away the stuff that's too small and the stuff that they simply didn't like. They really only NEED 5 everyday outfits plus 2 or 3 dressy outfits, but they'll probably want double that for variety. At this point, our plan is to give away what they really won't wear, and buy only the amount they need when Leah's ready for the next size.
Here's how I look at the whole issue of giving away stuff that I could still use, but just have too many of: If it's sitting in my closet, not being used, it's being wasted. It's so much better to give it away to somebody who's going to use it!! Right before we moved, we kept telling ourselves "It's going to cost money to KEEP this. Is it worth it?"