I live in Oologah, just west of Claremore, OK.
66 is in pretty good shape until you reach Tulsa, then it becomes 11th Street. Still not all that bad, but it has a lot of "detours" due to new construction....
If you are not in a hurry, there are several scenic things to see and sample the taste buds over...
One of those is a Cafe that I keep forgetting the name of in Tulsa, I think it is/was called "Corner Cafe".
the owners purchased our local cafe in Collinsville which had fallen on bad times with a couple of recent owners, and they have restored it back to its' old glory and good food.
In Catoosa, OK take time to see the Blue Whale,
also in Catoosa, please visit the Historical Museum.... I spent an hour there last year.
Address: 217 S Cherokee St #201, Catoosa, OK 74015
Phone: (918) 266-3296
After you leave Tulsa, you can get back on 66 and see a lot of historical sites.
West of Oklahoma City, it gets pretty much swallowed up by I-40 but there is still a lot of it to ride on away from the freeway... just follow the road signs "Old 66"
EDIT: back after supper....
In New Mexico and Arizona, Old-66 is hard to find except in a few of the towns that have fought to preserve it.
I lived in Edgewood, NM for 10 years, great country.
and in Mesa, AZ working in Phoenix, AZ for 20 years.
I miss that part of the country, but that isn't where my wife wanted to be in our Retirement years,