Hmm. Well, might not be the most healthy alternative, but Sam, have you tried having a bagel in the morning? It isn't sweet like cereal, it isn't squishy like oatmeal, feels like substantial food expanding when it hits your stomach, and yet isn't as heavy or as product-y as a sub? I swear, it's a pretty magic breakfast food, nearly the entire east coast lives on them for a reason! And maybe try tea or iced tea as a substitute for soda, I notice for myself that the nice acidic feeling tea leaves on my teeth is very similar to the acidic-carbon feeling that soda leaves in the after taste, it might be that "scoured" sensation that's making you miss soda. The carbon might be the big factor for you, not the caffeine.

(And uh, I have not attempted the stairs yet. I'm still brainstorming ways to change into socks and sneakers at work without attracting comments/attention x_x No spectators please :| )