We have a cooktop range (if I could go back in time 18 months, we wouldn't, but that's neither here nor there ;-)) and my husband has mentioned that his old tin teakettle doesn't seem to heat water as quickly, probably due to the ring on the bottom. He's a bit of a traditionalist and won't just use my coffee maker to heat water and I doubt he'd appreciate an electric water heater because "it would just take up more counter space" so I thought a glass teakettle would be a useful Christmas gift. I just assumed they would all be flat-bottomed but reviews on a few on Amazon have indicated otherwise. Does anyone know of any specific models that have a smooth bottom? Doesn't necessarily have to be glass but I would prefer it to be under $50. Thanks!