J M.
Yelp
This place is the coolest. Yes, cooler than the Rose Bowl. Free to get in, easy structure parking for $2 (enter on Del Mar), and mostly in the shade.
Great assortment of random art, toys, junk, some furniture, boots, et cetera et cetera et cetera. Particularly well-stocked and well-organized vinyl vendors. Overwhelmingly antiquey vintage stuff, but also a few plant vendors and swap-meet type people. As with any of these things, I sometimes get the impression that some of the vendors might live in their hoarder vans, but they tend to be very nice. Haggling seems to be the norm, but I'd rather avoid the stress than save three bucks.
Dealie takes place the 1st Sunday of every month. I think it opens at 8, and I've had no problem getting in as late as 10. The main set-up is in a parking garage, which cuts down on your sunscreen expenses, but there are also two smaller outdoor sections. The parking structure is centrally located, so if you have to drop off something heavy, it's not the end of the world. Student groups also run some food booths, so it's easy to get some fruit or a basic breakfast sandwich or something. Not too much seating, but the whole thing can be done in maybe 3-4 hours. Some of the vendors start packing up as early as 1, so don't dawdle. Oh, and real, non-portable bathrooms!
So yes, way better than the Rose Bowl. Easier access, cheaper, and more comfortable all around. It's smaller, with "only" about 400-500 vendors, and does have fewer furniture and other large item offerings, and not as many clothes. You also won't find $5 plastic sunglass booths or piles of Forever 21 dresses at PCC, but I'm ok with that.