Grilled Vidalia onions are also easy and tasty. I’m posting from my phone, so linking is difficult, but you can easily Google a recipe.
You mentioned the contents of barbecue sauce in a barbecue thread? What are you, a sadist? 
But, yeah, having googled California barbecue sauce, it’s true. I can’t remember which states don’t us tomato based sauces.
Masochist is more like it. Deviation is Heresy. The One True Sauce jihadists will be out in force. I will admit that, despite being a purist on other culinary subjects, I’m rather ecumenical on sauce. My preferred form of worship is North Carolina, Western Reformed. But I’ve been known to attend services in Texas, KC, Memphis, even Tennessee. But South Carolina and Alabama? That just ain’t right.
Thanks to all for the Texas Caviar suggestion. It was perfect.
Fresh tomatoes and tomatoes in sauce form are so different that I wouldn’t worry about it.
Personally, with barbecue of any type, I require slaw to cut through the fattiness of the ribs. I like my slaw with a nice, acidic bite, which means no mayo (or very minimal mayo) for me. If you want to showcase regional American cuisine, you might want to try something like a Memphis mustard slaw, which is traditional but a little bit different than the form of slaw they’re most familiar with.
I’m also a big fan of greens, so when I barbecue I like to have collard and mustard greens, as well. Barbecued beans, too. Cornbread if I feel like it.
If I’m going a little less traditional, then a grilled assortment of vegetables works well: eggplant, zucchini, red peppers, and corn. I also like combining Mexican influences into a barbecue, so I enjoy a homemade roasted tomatillo salsa to serve as an appetizer with chips while we’re waiting for the main dish to be ready.
Barbecue is not the place to get fancy and too creative, IMHO.
ETA: Oops, didn’t read the final post where it says this event already transpired. :smack: