You've come the closest so far. Yes, you go up in steps, but the trick is that you decrease the size of the step each time you go up so that the worst case for each step remains constant. The worst case would be 14 drops. I'm disclaiming here that I didn't think this answer up myself; I'd heard the question and numerous answers myself sometime back because I was researching precisely these kind of (stupid) brain teasers in my quest to get a job.
Drop the first orb from floors 14, 27, 39, 50, 60, 69, 77, 84, 90, 95, 99, 100... (ie, move up 14 then 13 floors, then 12, etc) until it breaks (or doesn't at 100). Call the first floor at which it breaks n and the previous tested floor n'. Then try the intervening floors (n'+1 .. n'-1) with the other orb.
Worst case is if correct floor is 13,14,26,27, etc which require m drops with the first orb and 14-m drops with the second.
If you map it all out, you'll see that it holds together. I have yet to see a better answer, but would love for someone on /. to find one :)