I would have to say I'm not a major sandwich person. Generally I can take 'em or leave 'em, but here are some examples of recent Bay Area sandwich explorations that are worth knowing about and taking. Ike's Place, the new and controversial extraordinarily popular SF sandwich place now has an outpost in Redwood Shores and soon at Stanford. Each sandwich is made to order so the lines are often due to people waiting for the sandwich they ordered to be ready. They come out warm on a just rightly crisp roll (your choice, but most prefer the Dutch crunch). I had the justifiably famous Menage-a-trois ($8.98), with Halal chicken breast, honey, honey mustard, BBQ, pepper Jack ( substituted regular jack), Swiss, Smoked Gouda. Great texture, flavors blending into a semi-messy whole. Sheila had the pizzle, chicken with bacon and cheddar, also terrific ($6.96). There's no place to sit right at Ike's located in a non-descript office building, but right outside is a pristine Shores park, perfect for a nice day picnic.
When I worked in San Francisco, a reliable treat was the roast chicken banh mi from Saigon Sandwiches on Larkin. Nine years later and it's still true. $3.50 buys a perfectly crispy French roll filled with nice chunks of flavorful chicken pieces, shredded carrots, cilantro, peppers if desired, and caressed with fish sauce. The roast pork and pate are also good. Often a line.
The Mexican torta is one great sandwich and two of the best are: La Casita Chilanga in Redwood City and Mexico Bakery in San Jose. Chilanga has a few more choices and other Mexico City specialties besides tortas. I had the tesorito ($6.25), smoked pork leg, which is like a combination of bacon and prosciutto, with lettuce, avocado, and other fixins, large and filling. Fresh thin chips and salsa are free. At Mexico Bakery, which also offers a very decent Oaxaca tamale and a great pound cake with chocloate frosting, I had the milanesa torta, thin slices of pan-fried beef with avocado, tomato, lettuce, chilies, and mayo. Freshly made and delicious. The chicken torta is similarly thin sliced and pan-fried.
A new place in Sunnyvale that looks like it's aiming to become a chain is Adamson's French Dip, that brings new appreciation to an old classic. The Prime Rib dip at $8.95 is nice-sized and filled with medium rare slices of real prime rib. It was better than the BBQ tri-tip at $6.95. A root beer float was the perfect accompaniment. It's a small menu, but everything is cooked with attention.
Lack of time kept me from retrying two all-time favorite sandwiches but I'll still mention them: The Italian meatball at Mario's Bohemian Cigar Store in Washington Square and the Godfather at Redwood City's Woodside Deli.