The CRJ is a nice plane. I've been on 3 of them (all with Comair) and its a nice, quiet little RJ.
The 757 flight- You'll probably have drink service, and you might get to watch some Delta Horizons, a nice little entertainment program with a sitcom, sometimes a music video (Delta VJ) and CNN In-Flight, among other things. I like the 757, It's a really neat plane, and I always look forward to flying on it.
I've never been on the 767-300ER. I've been on a few 767-300s, and they were pretty nice.
The 727 is a classic! Have fun on the 727!! I hope I'll wind up on another one!! You'll probably get drink service there. The 727s are nice planes.
CVG isn't a bad airport. I haven't been to the main terminals since '98, so I don't remember much about it. And I only got to sit in the Comair terminal for a few minutes in 2000, because of a tight connection, so I can't help you there.
ATL is my all-time favorite airport!!!! I LOVE it there. If you have time, try and go to Concourse E. It's totally different than the rest of the airport. Plus, there are now TV monitors at each Delta gate, (except in Concourse E) which tell you the approximate boarding times, aircraft info, current weather in your arrival city, etc.
-And for whoever asked above, there are no McDonald's locations at ATL.
A Burger King in each terminal, and a few Wendy's spread out throughout the airport. They don't have Chicken Nuggets, if that's what your looking for- I tried already.
FLL's pretty nice too.
A310/319/320/321/333, ARJ, BN2, B722/73S/733/734/735/73G/738/739/744/757/753/767/763/764/777, CR1/2/7/9, DH6, 328, EM2/ERJ/E70/E75/E90, F28/100, J31, L10/12/15, DC9/D93/D94/D95/M80/M88/M90/D10, SF3, SST