Hard to fit biker

Too tall, or too short... those seem to be problems with bicycling. I know that when I bought my last bike, the store was filled with giant-sized bikes and I had to search around to find one small enough, since I'm not even five feet tall. The sales clerk had to haul out the kiddy bikes that were apparently hidden somewhere in the back, to find one that was a good fit. I guess my question here is... how important is that perfect fit? I mean, I know that the bike has to feel right to the rider, but does it have to be perfect? My husband is average sized and the clerk spent what seemed like years trying to fit him to the right bike. I thought at the time, that it was overkill but hubby came away happy, so I guess whatever works, right? Are you a hard to fit biker or can you just walk into the store and come out happy in a few minutes?