My parents used to have a ski house right on the Mad River in Waitsfield, and my wife is from Shelburne, so I have fished that area a lot. Hm, so, without burning any secret spots, here goes:
The Mad gets stocked and has good spots, but I haven't fished it since Hurricane Irene changed everything a few years ago, so the best lies have probably shifted since I knew some of them. It also has some nice blue line tribs where you can always pick up a few wild brookies even in the heat of July and August -- but that's all I'm going to say about that! If you go north to Moretown and east up over back roads to Northfield Falls, the Dog River up and down Route 12 has been managed for wild trout for many years, and harbors energetic rainbows and some big, wily browns as well as native brookies. Or you could go west up over Route 17 to the Huntington River, but it gets pounded harder than the Mad or the Dog because it's closer to Burlington. There are a lot of good spots along the Winooski including the confluences of the Mad, Little, and Dog Rivers, as well as the stretch under the Winooski Street Bridge in Waterbury. If those spots are busy (as they often are, especially on weekends) you can drive along the south bank of the Winooski anywhere from Montpelier down to Richmond and find secluded pullouts. Or if the rivers are getting warm and you're up to a challenge, strap a float tube on your back and hike up the steep trail at Smuggler's Notch to Sterling Pond, and cast #16 peacock caddis to eager stillwater brookies. If you're looking for warmwater fishing, the Waterbury Reservoir is a popular spot for smallmouth bass and yellow perch. The Fly Rod Shop in Stowe is the long-established shop in the region and the birthplace of (the late lamented) Diamondback Rods. Its current owner, Bob Shannon, is becoming something of a personality on the winter fly fishing show circuit, and he keeps three or four guides busy. I've found they are pretty generous with advice if you walk in on a slow day. There is also a new fly shop called "The Silver Trout" that is just getting started right in Waitsfield where I imagine you will soon be able to get the most detailed, or at least recent, local advice.
I still get up there reasonably often, so come fishing season, message me and we can try to meet up for a day on the water. I'm always looking for fishing buddies.