Fortunately, my grandmother had tipped us off to a music museum in the area. Although we almost missed it as the outside looked like an office building, the Museum of Making Music was in fact just next to Legoland, and only cost $5 admission vs Legoland's $57. I enjoyed the exhibits, including really odd-looking "harp" guitars which I had never heard of before, synthesizers, and a plexiglass grand piano which I convinced boyziggy to play, to entertain the Red Hat Society ladies touring the museum. His performance went over well with them, and I got a couple of short videos which I'll post as soon as I have reliable Internet access again.
The sun had come out again by the time we left the museum, but we didn't feel like spending $114 for two hours at Legoland, so I ate the $10 parking fee and we went back to Coronado. On the way back we stopped at All Vegan, a "shoes, chocolates, and other necessities" store in University Village, which had a great guide to other San Diego veggie-friendly stores and restaurants. We each bought a new pair of non-leather shoes and a wallet, and also indulged in vegan caramels.
That night we took grandma out to a great Mexican restaurant from the veggie guide, Rancho's, which had delicious vegan cuisine as well as traditional omnivorous fare. I had a trio of enchiladas, containing avocados, refried beans with mole sauce, and tofu, and grandma and I enjoyed margaritas as well.