Hmm, would be interested if anyone comes up with any ideas. Know what you mean about flylady being too little at a time (though the e-mails sometimes make me get off my backside). The goal I aspire to starts pretty much as you suggest - gut a room at a time, then ongoing do one or 2 rooms a day (assuming you have time each day, or whatever suits) What I intend to do is:
Step 1 - big clean - each room, pull all "stuff" into centre, clean/dust/hoover - put things back, and have a box for things that don't belong in that room. Then have coffee, and empty the box putting things where they do belong. Next day, next room etc
Step 2 - ongoing - have a daily routine like Flylady eg make beds every morning, wash up after breakfast, empty wastepaper baskets, sort and action post as soon as it arrives. Evening, wash up and leave kitchen surfaces clear, check rooms are tidy.
Step 3 - have a day of the week assigned to each room/type of room - kitchen, bathroom(s), bedroom, kids' rooms, garden. (and any others you may have eg office, playroom)
But it's all very well to think about it, it's just doing it that's the hard bit (I'm using 4 month old baby as excuse - not sure what excuse was before...)
Oh, and declutter before you can realistically keep on top of tidiness! I'm trying v hard to be more ruthless about what is actually necessary.