You will find RV Parks with full hookups on Grand Lake O the Cherokees. There are more than 70 private RV Parks and public parks around that lake, which is exempt from the "no shoreline development" rule imposed on many COE lakes.
I am familiar with Cedar Oaks and Bear's Run in Grove, and Water's Edge on the Langley side of the lake. These may not have a full service marina, but do have dock space. Whether or not ramps are available at any particular time will depend on lake levels; just this week some ramp (and camping) facilities will close for flooding.
There are a half dozen marinas around Grove, a short drive from the Grove RV parks. There are at least two dozen marinas in that part of the lake, but most are on the other shore, around Afton and Bernice. I am not familiar with most of the parks on that side of the lake, we go to Grove for the town facilities.
Some of our COE lakes have concessionaire marina operations, and some of these marina operators also operate RV parking. I haven't been in any where I would take a family for a vacation, the ones I've seen were more like fish camps.
State parks on our larger lakes usually have at least one marina. It will not always be co-located with a RV campground.
Most of our COE and state park RV campgrounds do not have sewer hookups, but a few Oklahoma parks have some FH campground loops. You need some lucky timing to get into those, we don't do campsite reservations in our state parks. The Post Oak area at Lake Thunderbird SP (northeast of Norman) comes to mind. This state park also has two marinas, but not at this particular RV campground, but one is on the same side of the lake.
