We did our level best to visit every restaurant in Vilnius, but eventually gravitated to a few favourites.
"Traditional Lithuanian" - Cili Kaimas, a chain but reliably good food and relatively cheap - you could eat a huge meal for under $8. Our favourite was just off Gedimino Prospektas.
Salads and Sunday brunch - Mano Guru, near intersection of Vilniaus and Labdariu gatves. Meal sized salads, about 15 to 20 Lt (around $5 - 8), pancakes, kose (warm cereal, yummy) maybe 8 - 12 Lt. Restaurant is non-smoking and doesn't serve alcohol, so closes around 8 pm, but is open for breakfast every day.
Pizza: Cili Pica (pronounced Chili Pizza) is a chain run by a Lithuanian American so it's one of the few places that actually serves something approximating traditional pizza, though there are still always two bottles of ketchup (regular and Mexican) on the table. A cheese pizza for one (about 20 cm) costs a little over a dollar.
Kukabura, an "Australian" restaurant, also serves decent pizzas for about a buck. It's in the basement of a store in Gedimino
Pr.
ZaZa's is the hip place to hang out, you'll see models and politicians there in the evenings, and can get a pizza for about $2. It's on Vilniaus g. near the intersection with Gedimino
Pr.
Chinese: I don't recommend this in Vilnius unless you're desperate for the taste - they freely substitute traditional Chinese ingredients with whatever's available locally. "No bok choy? Okay then, cucumber." And it tends to be more expensive than other options, but would suggest Rytu Perlas in Labdariu g. $10 +/-
Indian: Sue's. Just off Gedimino
Pr, with a view of Cathedral square. De-lish, and have items ranging from mild to nuclear. Pricey compared with other options, but great atmosphere and food. $15 +.
Fusion: G-Lounge. Unique atmosphere in Vilnius, tres hip but they let us in anyway. The food was superb when we started going there, but the changed the menu close to when we left, took out some of our favourites. Lots of Asian influenced flavours. Wasabi mashed potatoes and sweet mashed potatoes were awesome sides, if they have the seared tuna, get it, and my husband and I still crave the chocolate ganache cake. Fancy anniversary dinner for two with dessert and wine was $35. Pilimo g. - you'll see the sign and then go down a small alley and upstairs.
Breakfast: Prie Angelo, Uzupis. Across the river from Vilnius, near the angel statue (that's what the name means). Delicious caramel crepes, if that's your sort of thing. $5 ish.