Hi Cathy Bannister,
I too have seen some ebay auctions claim that the large swans were by Rainbow and you are right; Rainbow did do some similar shaped swans, just not as big. Since their business was about making hand made "art glass" items; their glass is much more optically clear and the finishing work is done so much better.
The Sooner, Cherokee and Bcraft items tend to appear foggy and or gray looking in the colored areas and I assume it is because they were made from recycled glass, which in its original forms (jars bottles etc.) was not the same quality-type of glass used in making art glass. A side by side comparison says it a whole lot better than I can in words.
Both Kanawha and Rainbow glass were\are in West Virginia, not very far from one another and perhaps the Sooner, Cherokee and Bcraft swan designs etc., were inspired by items being made at Rainbow. There are or were many glass makers in West Virginia (a very small state) who produced hand made glass similar to the Murano Glass style.
Some of the better known glass makers, who made some Murano-style-type items are or were....
Blenko Glass - Milton, West Virginia
Bischoff Glass - Huntington, West Virginia (Many of their shape molds were purchased by the Indiana Glass Company, who made some reissues in the 1960s)
Hamon Glass - Scott Depot, West Virginia
Pilgrim Glass - Huntington, West Virginia
Viking Glass - New Martinsville, West Virginia
Morgantown Glass - Morgantown, West Virginia
Bonita Glass - Wheeling, West Virginia
Erikson Glass - Just across the Ohio River from West Virginia, in Bremen, Ohio
There were many more, not so large or well very known glass making businesses, plus a good deal of glass was being made by local individuals, at their homes.
I lived in western Pennsylvania and had relatives in southern Ohio and across the river in West Virginia. I remember visiting the area often in the 1960s and early 1970s and it was like a glass making Mecca at that time, The three major industries in the area were coal, steel and glass. One could drive through towns in West Virginia and see big displays of hand made glass items for sale in the front yards of residents, who usually worked at one of the many glass factories and who had a small set-up at home for making their own items. These items tend to be impossible to ID when found today, since these folks didn't sign their work, nor did they invest any money to put paper labels on it.
When the first big oil and gasoline shortage came about in the 1970s; most had to give their glass making hobbies up because of the high fuel costs. Today; in hindsight I wish I would have thought to photograph the sights and all of the glass I saw back then, but sadly I was too young to be so sensible and had no psychic abilities either lol!
Personally I believe all glass (no matter who made it) has its own unique characteristics. Some prefer the very refined, high quality glass, some prefer the middle of the road type and some prefer the more rustic type. Me; I admit to being a snob in the area of glass that I like, but I am almost certain that I wouldn't enjoy my glass collecting hobby as much if everyone else liked and collected the same thing as me.
Glass is somewhat like music in that sense.