OK girls,
I have a little experience with this, but you may not like what I am going to tell you..
The first quilt from what I can see, looks to be made in the 1930s not the 1800s. .
As to value, tops like this were selling for around $50 - 75 depending on the pattern and condition as well as the workmanship.
Today, the prices have droped a little due to the economy.
This one is a common design, but the addition of the solid blue diamonds is a little unique.
As to whether you should quilt them or not.. it also depends on the age and condition of the fabric. This is a very personal choice also. And if you as three people, you will get three different answers.. But this is my opinion, after having thought about it for a while...
If the top is not of historical significance.. and the fabric will hold up to it, I think it is fine to go ahead and make it up into a quilt. Especially if it is a family quilt as it will last longer and be more useful as a quilt than a top. I do feel that it should be finished in the manner that it was intended.. in other words, if it would have been hand quilted, I would hand quilt it.