We typically make it down at least once a year. I would consider Cincy Aquaholic the resident expert on Lake Cumberland. Until he upgraded to a larger boat he was down there at least every 3rd weekend. (I am sure he is down there this weekend for the annual poker run.) We usually stay at Woodson Bend resort.
http://www.woodsonbendresort.com/. We have friends that own there so we usually stay with them.
We have stayed with friends here as well
http://www.goldenpondresort.com/kentucky-vacation-rentals.htm. Both of the places were nice but they are privately owned and rented so the quality may vary but I think for the most part they are pretty nice.
As Sierra stated many people rent houseboats for the week. I lurk on the lake cumberland.com forum that Sierra posted a lot of good info there.
As far as the lake it is very deep with rocky shores. No real beaches to speak of. Many coves, some are as extreme as the pictures that were posted from lake Lewisville. Others are more family friendly. For all intents and purposes it is a "dry" area. You cannot purchase alcohol around the lake so you must bring enough beverages to last the duration of your stay.
I don't know where you are traveling from but not much farther is Norris lake We went there this summer as well See here.
http://www.smwebhead.com/phpBB3/viewtopic.php?f=2&t=4293 I like Norris better than Cumberland. Dale Hollow is also close to this area and is supposed to be beautiful although I have never been there.
I hope that helps.