I'd say physics and chem events are the best to stick together in since the process skills are usually similar throughout the event, and the type of mind needed is also similar.
Yeah, I'd disagree with you on the DP/Ecology idea, rocketman. When it was oceanography and marine bio there was a tiny bit of overlap, but the focus of each event was totally different.
Events: Ecology, Herpetology, Cell Bio, Entomology, Sounds of Music, Circuit Lab, Chem Lab, Disease Detective, Dynamic Planet, Five Star, EggONaut, Enviro Chemistry, Fermi, Quantum Quandaries!
Nationals: Wichita: Ecology-4, Entomology-5, Team-11; DC: Sounds-1, Team-11