Date: 4/23/2008 7:29 pm EDT
The industry standard for a flat subfloor when installing traditional ceramic tile is to have not more than 1/4" variance in 10 feet. Avaire tile works fine if installed over a subfloor meeting that criteria.
Did you use the recommended primer for the Self Levelling Compound? The primer seals the substrate and aids the flow of the self leveller and is a must.
If you choose not to add more leveller as already suggested then your next best-bet is to rent a (17") floor-machine and buy some sanding discs. The discs will grind the surface and once you get the hang of it you will be able to feel the highs and the lows and figure out the process.
Traditional ceramic wouldn't be any easier or any better than the Avaire tile at this point.