Last summer, I gave my girls FleaTreats and used Vet's Best Flea and Tick spray (all natural) on them, their bedding, furniture, carpets, etc. After spending the summer in SW Louisiana, I ended up having to get capstar (Bella gets flea dermatitis) from the vet to get rid of the fleas.
I continue to give them FleaTreats (which does contain brewers yeast), and use Vet's Best on furniture/carpet, but have decided to use 1/2 tube of K9 Advantix II on each of them this year (like you said, the winter didn't do much to kill off all the bugwuggies). I keep Bella and Tillie in long coat... those who keep furbabies hair short may have better luck with Flea Treats and Natural remedies alone