We have the best luck with BOSS (black oil sunflower seed) so you might want to get a small bag and add that into your mix. We don't use mixes at all unless I happen to win a contest or take advantage of a giveaway that involves seed. (Yeah, I don't go after money prizes! I go after the precious seed prizes!
) We just offer BOSS, thistle, suet and now freeze-dried or roasted meal worms.
I suspect, though, that the main delay for you is just that they have to find and get used to your feeders. If you see birds in the bushes but not at the feeders, you might want to move your feeder a little closer to the bushes. Birds feel more comfortable if there is cover within a few yards or meters. Keep the feeders at least 10 feet (~3 m) away, though, or squirrels can leap off the bushes to your feeders...and they eat like little piggies!
As for cats in the windows putting them off--we have our feeders just outside the fence (about 10 feet). The dogs sometimes line up at the fence and stare out at the activity under the feeders--both squirrel and bird traffic--and they're totally ignored by the wildlife. They learn pretty quickly just how far the dogs are likely to come, and I suspect that they'll get used to the sight of cats at the windows, too.