I love Sacks for take-out. They have some of the best sandwiches around. I especially love the Impressionist (the veggie sandwich) and the salmon sandwich (forgot what it's called). Their bread is always fresh and they have lots of delicious sandwich add-ons like fresh avocado and sprouts.
They're no NY deli, but then again, they're not trying to be.
Get your sandwich to go or have them cater a lunch. One thing to keep in mind that their hours are unpredictable and that they're never open when you want them to be!