Ha ha. I ride that all the time. North, maybe not worth it. But south to the TN line, definitely worth it, especially this time of year. The bridge Purplezinger mentioned is open unless it's been closed recently. Never had any problems with it. One lane so come up slow. Very scenic crossing with good hills on both sides.
If you're in Lex, one ride you HAVE to take is out Richmond Road to Athens to Boonesborough. Get lunch at Halls on the River. Then you could go from Boonesborough and pick up 25 South in Richmond. That will avoid that bridge if it is in fact closed. In fact that's better than the pure 25 route with the bridge. If you're in Lex for awhile, take 52 from Bryan's Station Road to Blue Licks. A lot of it is like a one lane paved wagon road.
When you hit Cumberland Gap take a side trip of Pinnacle Mountain. Several full lock turns up a steep grade... Several good places to eat in Cumberland Gap.