The hike of OML is not as steep as the hike to CC. The beach entry is not as steep at CC as it is at OML. It is a quicker entry (if conditions are good) at OML than at CC. The exit is trickier at CC than at OML.
OML is by far a better dive and is more likely to have better visibility than CC. The reef structure at CC is comparable to OML, but it is all in the 20-45' range. If you like a 'swim around on area, then head to shore' type of dive then CC is a good choice if there is minimal to no south swell.
If you are ready for an 'enter at point a and swim to point b' dive and you have the skills to navigate said route and can handle the occasional surface current then OML is a dive you can do.
There are other people here far more experienced with OML here than I and I am sure they can give you some good tips and warnings on when it is advisable not to enter. Obviously, if you drive here and conditions are above your skill level, DO NOT DIVE OML. You will get seriously hurt or killed. Use your brain and know when to thumb the dive before you get in the water.
The same goes for CC. If conditions are not at or below your comfort level, call the dive. The entry zone is very treacherous. There are submerged rocks and holes all throughout the surf zone. You can break anything from an ankle to a neck if you put your foot in the wrong place or get hit by a rogue wave in the surf zone.
The only real way to judge conditions is to see them with your own eyes. I wish I had a dollar for every time I have heard "It was really good yesterday." You can check all the swell models on the net and they will only give you an idea of what conditions may be like that day.
If you know someone who lives closer to these locations than you, use their eyes before or during your road trip. Have an alternate site plan in case one site is blown out. I called a friend from the site we had planned on diving before she left LA to tell her it was not worth her drive. I live 20 minutes from the site so I would have dove it with conditions as they were, but I did not see why she should put in a 1.5+ hour drive to dive in marginal conditions.
Good luck and remember, for big south swells, head north of the orange curtain. For big north swells, head to OCal (I hate that Ken!) If we have the misfortune to be hit with both... do something else!
Dove safe,
Robb
