I'd go with LL Bean Duck boots for midcoast - you're actually going to be dealing with a lot more months of slush and half-frozen mud than actual snow. If you're planning on heading inland frequently in the winter, get a pair of Sorrels for the cold, dry snow.

For gloves... I like Astrid for a huge pair of mittens to walk around in when it's really cold. But they're not waterproof. For waterproof maybe get something from a ski/snowboard store. (I happen to have Burton, but really anything marketed for skiing/snowboarding should be fine.)

Also you didn't ask about coats, but I like Canada Goose.