Here is my humble opinion:
If they are valuable to you as "antiques" or "vintage" items leave them as they are. Modern materials will de-value them in the market.
If they are valuable as cherished family heirlooms, leave them as they are, and document everything you know about them. Arrange for the future of these items. If they are really valuable, have them appraised, as is.
If you want to use them up, do whatever you like; they are yours, after all. Please don't use polyester batting!
Will the fabrics and stitching hold up to quilting?
Will the fabrics hold up to washing? Many old fabrics are fragile and will NOT hold their color when wet and the result can be absolutely disastrous!
Trust me--I know! I always test each fabric for colorfastness. If I have to replace it, I use antique fabric from the same era.
Whatever you do, document them now, while you have the information at hand (and memories do fade, unfortunately). Withouth documentation, inheritants rarely recognize the value of such things, or how to care for them; nobody will remember who made them originally, or when, or who finished them as a loving gesture.
If you don't feel comfortable finishing them, find a professional hand quilter. Communicate your wishes clearly, and pay her well.
We would LOVE to see pictures of them!!!!! Pleeeeease?
BlueBars

thanks for the advise. I will leave the two unfinished tops as they are then. The one that is already attached to batting I may go ahead and finish. I have never done any hand-quilting....but I have done just about every other textile craft known to man and seem to do pretty well with all of them....I don't think this will be too challenging to learn. I would love to post pictures. I'll do that tonight.

My mother entered a nursing home with alzheimers a few months ago, so I am afraid some of the history of these quilts has been lost forever. I do know they came from her side of the family. I am hoping someone may recognize the fabrics or patterns so I can nail down a date. that way, I'll know if they are the work of my Grandmother, or my great grandmother. I have old pictures of these female relatives too and I intend to create a document that has as much info as I can gather about them quilts and I'll include pictures of the makers as well. Another really cool heirloom I got Saturday is my grandfather's christening gown, and a picture dated 1904 of him wearing that actualy gown. Talk about a find!!

It's a very personal decision, but I can tell you from my own experience, it is possible to finish old tops into usable quilts. I do this VERY often, and my whole family use quilts that I've made using old tops I've bought. However, you have to be realistic about the shape the fabric is in...REALLY look at it and if you decide it looks in good shape, and you want to make a quilt from it, then 'have at it'. I use all cotton batting, and 100% cotton backing fabric, and hand quilt it. I make a label and apply it to the back of the quilt, that says where I bought the top, my name and when I made it into a quilt.
I wash mine in the machine, but NEVER let it agitate...that's where the problem comes in. Fill your washer with warm water, soap [not detergent] (and I always add synthrapol, to prevent fading...you can order it online but I've found it several times, lately, in quilt shops and even a sewing machine store.) Lay the quilt on top of the water and let it sink to the bottom....swish it around with your hand, let it soak for a while, and spin out the water...rinse and spin, being sure to look at the water. You may have to repeat the whole process process a couple times. Just don't agitate, and you'll be okay. When dealing with old tops, there are often yellowed spots, and it's best to just 'live' with them...don't scrub at them. I use a product called Nanny's Vintage Soak, which is a whitener for antique linens...but, I'm not sure it is available any more...get it if you can....it works. After the quilt is washed, place it OVER several clothes lines ....do NOT use pins to hold it up, but drape it over the lines...ins put too much stress on the fabric. I place mine over 3 lines I have in the basement, and that works will. I also place mine outside, over a big hedge I have.
I've done this many times and one of the things I enjoy most is finishing the work started by another woman, many years ago.....I like to think they'd be pleased.

I have not completly unfolded any of them to look them over completly, but from the parts of each quilt I have seen, they appear to be in excellent shape...other than some yellowing. I don't see any fading or thinning of the fabric at all. These tops have been in a blanket chest for many, many years.

I would give me a lot of pleasure to finish at least one of them, knowing who started it. What a wonderful connection to my past, and what a wonderful heirloom for my own children.

I'll look for that vintage soak stuff and see if it's still available. If I do decide to wash them, I think it would be safer to wait until after they are completed. Seems like they would be much stronger that way.

What wonderful information! I will print and save the above advice as it's a keeper. And, I agree about the quilter being pleased it was finished, or just saved if that is your preference.

I sometimes buy old quilt blocks at a garage sale that might otherwise have gone in the garbage. I think the quilter would be pleased it is now cherished - even if I never complete it. I do label them that they aren't family heirlooms so my kids know they aren't from family.
Linda