Al's French Frys (that's how it's spelled) in Burlington may be worth a stop, as it's a real landmark, but the food is just OK. It's cheap and quick , with thin hamburgers and pretty good fries, basically like a really old-fashioned McDonald's, with much more style. They also have soft-serve ice cream.
A few weeks ago we stopped at the Farmer's Diner in Quechee, and we liked it a lot. It's an active participant in the "local food" movement, and sources most of their ingredients locally. Part of it is in a real old diner car, which is cool. It's also attached to a fun Vermont store with a Cabot Cheese outlet inside, and fun Antique Mall, if you're interested. It's also closer to I-89 than you'd think, only 4 miles off the highway.
Frankly, when I go from Boston to Montreal, I go straight up i-93 to the Canadian border, then cut over on Canadian Rte 10. It's onlyt a few miles longer, but takes about the same time, and has much shorter lines at customs. Most importantly (and back on topic), I stop at Littlleton Diner in Littleton NH on the way up (great pancakes and brunch stuff), and/or Bishop's Ice Cream in Littleton (best ice cream I've found in NH), and on the way back I stop at Miss Lyndonville's Diner, just north of St. Johnsbury, which has excellent food, way better than you'd expect at a diner, cheap, friendly, and fresh.
Ok, Running south to north on Interstate 89:
Exits 1-2 I know little about. That's White River Junction and West Lebanon, NH area. Other folks might be better able to comment on what's available near the interstate in those areas. We usually just stop at Wendy's in West Leb if that's where we are at lunch time.
There are no restaurants within any sort of reasonable distance from the interstate off of Vermont exits 3 through 6 on 89. You'll find McDonalds but nothing else. Exit 7 has an Applebee's, which is OK in a pinch, it's a reasonable example of chain food and they have decent enough service and food for what it is.
Off exit 8 in Montpelier there's Sarducci's on Main Street, and Royal Orchid Thai on Elm street (just off of State Street). Both of these places have had reviews here on the new england board, and are good for lunches. I can't remember of That's Life Soups (also on Elm, near Royal Orchid) serves lunch, but their soups are wonderful.
Off exit 9 there's the Red Hen Bakery and cafe. They sell sandwiches and I think they might have soups, as well. Also a lot of nice Vermont products, and in the same building is Nutty Steph's and a great fiber/yarn shop. This is less than 30 seconds from the interstate. :)
Off exit 10 you'll find the Alchemist in Waterbury, and Stebu Sushi, as well as Ocha Thai (owned by the same people as Royal Orchid, another good thai place). Stebu Sushi is FANTASTIC. Also you'll find Kelli's Grill and Juniper's Fare, a little further down the road from those three places. Again, all of these places have been mentioned in reviews around here.
Off exit 11 is Richmond. Most of the good places to eat in that area are a little further from the interstate, I -think-. I'm not sure if Kitchen Table is close to the exit or not. But that's an outstanding place to eat from all accounts.
Exit 12 is big box land and home to Chilis, Longhorn Steak House, Quiznos, and a little American-Chinese/Japanese place called Asian Bistro. None of them are bad, but none of them are very special or high quality.
Exit 13 you have to go a ways before you hit any restaurants, though from what I understand thare are a number of decent places to eat on Shelburne Road (which that road eventually leads to), but a lot of chain stuff, too. I don't spend a lot of time around Shelburne road so I can't comment on food quality or proximity to the Interstate there.
Exit 14 leads into Burlingont/South Burlington. If you want to foray into downtown Burlington there are a lot of good lunch options (Single Pebble, Big Fatty's BBQ, and Sadie Katz deli (that's still open, right:) being three that I particularly like). However, parking in Burlington, especially midday, is a bitch. There's nothing especially great right near the exit. More fast food stuff, mostly.
Exit 15 I don't spend a lot of time around, so I can't comment on good eats nearby but you can't get back on the interstate heading north from exit 15 you have to find your way (by following the signs) up to exit 16. I tend avoid that sort of situation in an unknown area if I know about the situation in advance.
Exit 16 has Junior's not far from the exit. Some people really like Juniores (I love their baked ravioli) and others are less enamoured. I've never had a bad meal there, though I have had less than outstanding meals there. I still like them for lunch when we're up shopping at Costco.
From exit 17 on, I don't know what might be near the exits. My feeling is that most of them don't have much near the exits.
Hope this helps! :D
For breakfast or lunch I usually make a pit-stop at the farmer's diner in Queechee, VT - about 8 miles off the highway and well worth the drive. If you are near Waterbury, Vt for dinner check out the Alchemist for a beer and a great gastropub style menu.
5817 Woodstock Rd, White River Junction, VT 05001
23 S Main St # 2, Waterbury, VT