Kudos to the hummus! Sounds delicious.
You can also use mustard; maybe I missed something, but mustard is delicious in sandwiches, especially since you don't like mayo.
If you are eating your sandwich right away and not packing it for later; you can slather it with some salsa -- Yum!
Or, try pesto on your sandwich -- double yum!
If you are packing your sandwich for later in the day; keep all ingredients separate so your bread doesn't get soggy. You can even put your mustard or pesto in a small plastic container, and assemble your sandwich when you are ready to eat it. A little more work, but worth it to not have a soggy sandwich at lunch time.