Sawrey House. Bit pricey but absolutely stunning rooms/dinner/breakfast. We were headed there for Mrs Finn's 50th a few years back but had to cancel due to serious illness. Re-arranged for the following year and they remembered it was her birthday - flowers in the room, card, the works. Next door to Beatrix Potter's cottage.
Would second this. You may also want to check into The Tower Bank Arms pub which is about 100yards away from Sawrey House and it is a terrific place with fantastic beer - check out Loweswater Gold - award winning beer brewed about 2 miles away