Go to Hugo's in Portland Maine. Maybe someone else has already mentioned it, and if so, great, if not, look them up. I've been to many of the restaurants listed, including Hen of The Wood, and none of them hold a candle to it(none of the ones I've been to). Don't get me wrong, Hen of The Wood is very good in a rustic sort of way, but Hugo's is on a different level. I traveled from Montpelier just to eat there on my birthday, and it was one of the best meals of my life. Elegant, but not overly worked or contrived. Perfect complimentary plates. I'd suggest the starter menu since the chef there (at the time) had the skills and knowledge to define an amazing experience from start to finish. I think there was one course out of 8 that wasn't delicious, but even that was still pretty good. It's been a couple years, so maybe it's lost some of it's luster, but it had already been there for ten years when I went.
Oh, and I've heard pretty good things about the Kitchen Table. Anything to do with the Culinary institute is often hit or miss, but if you happen in on a good shift of students and profs, it can be an unexpected delight (though that's rare these days). J Morgans is mediocre at best; but their serving sizes are Flintstones worthy--so it's good for a nervous laugh. Skinny Pancake makes the worst crepe I've ever had--thick and tough and chewy with a heavy, leaden, under-seasoned and stringy meat filling; and their sides may be fresh, but they also run the gamete from unimaginative to just plain bad (raw root vegetable slaw with no dressing or seasoning--crunchy?).
For a great burger and fries, go to Three Penny in Montpelier--they also usually have some interesting sides (killer fried oysters, fried chicken livers, and assorted house pickled veggies--simple but fresh and good--especially with a Heady Topper to wash it down!)