Yes, you can. One thing, the car rental agencies around
Disneyland have very early closing times, and some don't allow after-hours drop offs! Unless the hotel you're staying in has a rental agency...one you want to use...in it, you'll have to get the ART or other transport back to your hotel, too. If you're like me and don't use credit cards, that makes it even trickier.
After doing much looking, I decided to go to Laguna the first day of our trip, heading their right from SNA.
Do not try cabs or any other public transportation. You'll either spend hours trying to get there one way or pay a small fortune!
Last time I used a limo service. In 2005 they charged me $100 round-trip. I have no idea what they're charging this time. You can find links to limo services on the OC and Anaheim websites.
At Laguna you have to park up the street that runs perpendicular to the main beach...or mess with hourly parking closer to the beach.
We're really looking forward to our visit there. Due to the time changes, we're doing what will be lunch for us by going to a late breakfast at Zinc. I was searching everywhere for info on where to eat...then saw it on Rachael Ray. Then the kids will have all day to play and explore. We'll do dinner at BJ's and head back to our hotel. The nice thing about a day at Laguna is that you can play it by ear and do whatever you feel like!