Comfortable...well, I know that we can live up or down the scale, depending on what we want to do. Our normal life expenses are pretty cheap, on the same level as yours. It is the wild and crazy stuff that blows our budget, like travel.
I think that we'll be fine with what we've got saved, not touching it, if we leave it til I'm a bit over 50. That is dependent on Mr. Market, of course, but that's my gut. I just figure that for us, work and not-work is a flowing thing, where we work sometimes, and don't work sometimes, until we feel like we need to retire full-time. The Travis McGee system is what I call it, after the John D. MacDonald character of the same name.
I am not looking for sure things and permanent retirements. I can do something, somewhere, if I need/want to, or I can do nothing if the markets are good. It is a long time, hopefully, til we die, and I just want the luxury of time off between jobs.