A compilation of bits on my last trip out to North County (Jan 2011). The drafting and such is between the PCH and Vista, around Carlsbad / Palomar Airport. The cool cars are on the PCH, mostly near Torrey Pines (Porsche was closer to Carlsbad). Lake Wohlford descent was on way back from Palomar, going into Escondido. By then I was going via Lake Wohlford -> Harrah's -> South Grade. Then turn around and go back the same way I went up.
Oh, a tip on Palomar - I thought Harrison Grade was South Grade (I had no map, I was just going off written directions), but it is definitely not. Harrison is so steep, and gravel, that I couldn't get the rear tire to stay planted even while seated, and the front would get light if I stood. It was really steep, and zero traction, and scary when I turned around and went back down the little bit I went up. If you go from Harrah's then you simply turn right at the intersection and you won't even have the chance to make my mistake of going up Nate Harrison Grade. There's a small convenience store just before that right, it was my default refueling spot. I would also get a postcard at the top of the mountain and mail it from the tiny post office up there, so it would have the postmark.
https://www.youtube.com/watch?v=e_o8CFeGG_g
I only really know about north of Torrey Pines. South of there it gets busy, and if I got that far I was already looking at 5 hours round trip so I didn't venture too far south of that (La Jolla I think is as far as I went). North of Torrey Pines, it's nice. Check out Lilac and W Lilack Road, Champagne Blvd (Lawrence Welk resort). For me, from CT, PCH was nice and relaxing, wide shoulder, relatively smooth roads, and, again, for me, nice stretches of road with enough lights etc to break things up. Also some cool stuff to see. Like by Carlsbad there's a place on the beach where RC plane people meet, for example, so I'd stop and watch for a bit. There are surf areas as well. If you want seals they are here and there but I didn't go looking for them. etc etc.
How old are the kids? If they're young, Legoland is in Carlsbad, and we went there with my son. I didn't ride that trip but that was fun.
And if you're around Balboa Park Tues Nights, there's track racing at the velodrome there I think. I think it just started last week.