Yep, I'm another one who has had the problem.
I use Frontline (spot on) for my cats each month. Thing to remember is that it can take up to 24 hrs for it to kill off the fleas, and as mentioned before they may be re-infested from their surroundings. The spot-on will continue to work, you just have to remember that a further 24hrs might have to elapse to kill the new fleas. It just seems that the Frontline is not working, when really it is, and yes it only kills adult fleas.
Household sprays - the best are bought from the vet, they tend to be stronger and last for a whole lot longer. I use a make from Vet-Kem called Acclaim (not sure if it is available in the US). This spray is used on carpets, soft furnishings etc. It lasts for twelve months and unless you frequently wash sofa/chair covers, throws (as I do) or change a carpet etc. doesn't need to be re-applied within the 12 month period. This spray, as with most, is a growth regulator which prevents eggs and flea larvae from maturing into adults and helps to break the cyle. The spray also contains an insecticide that kills adult fleas which may continue to hatch in the first few weeks after spraying and help kill fleas which may be tracked in from the outside. (These fleas may seem to re-infect your pet but remember that is when the frontline will take care of it)
What has to be remembered is that none of the products are instantaneous, but together will over a period of a few weeks take care of the problem.
We all want an overnight solution to the flea problem, unfortunately that isn't possible as the strength of the ingredients required would put our kitties health as well as our own in jeopardy.
Occasionally my lot will come in with a flea on them, if I can't catch it I ignore it as I know (from experience) that with the precautions I have taken it won't survive longer than 24 hrs and re-infestation of my home is not an issue. It should be noted that I live on a farm (with sheep) and that since I started this regime I haven't had a problem, and trust me ticks as well as fleas used to be a big problem. All my cats are inside/outside cats and have the freedom to roam the fields, woods and barns in the surrounding area as they wish (impossible to treat an area the size of a farm). They are never bathed unless they happen to have fallen in a ditch and that is because they look just like walking spikey heaps of mud.