Thank you all for the crab cioppino suggestions, my mom really wanted to go to Scoma's. Recommendation - if you go on a Saturday and want a decent table for lunch, don't go at 11:30am when they open. (They don't take reservations.) We got there around 11:15am and sat at the bar; by the time 11:30am rolled around, the waiting area was packed.
There was a suggestion here to sit upstairs for a better view; unfortunately the upstairs area was closed (at least for lunch). We did manage to get a window seat, with a very friendly (and funny) waiter. There is a menu item called "Lazy Man Cioppino" (I'm guessing that it's shelled for you) but the table behind us asked incorrectly for the "Poor Man Cioppino". Our waiter made the comment (in a nice way, not condescending) that you only get the shells with that version!
I wanted to get something that my husband wouldn't eat (allergic to seafood) and my dad wouldn't cook (buying crabs from Chinatown and cooking them fresh). So I chose the seafood cannelloni (sp?) which was very rich. The tomato-ey sauce helped to cut some of the richness. It was full of scallops, some kind of fish, and crab. It came also with pasta and veggies (cauliflower, broccoli and carrots).
My mom had her crab cioppino (NOT the lazy man version). She put on the bib and went to work. I can't believe it, but she finished every piece of crab - she went through 4 linen napkins!
Both our meals were $25 (give or take a dollar) A little pricey in my opinion, but my mom had a really nice time so I'm happy. I wouldn't call it a value-priced meal, but when your mom is set on it... :)
Thanks again for all the suggestions! Maybe Mother's Day...