I know what you mean about having too much choice; Alnwick is a place I have always found to be very difficult to choose. You have so many hotels and B&Bs to pick from that it can be tough to pick. My recommendation would generally be to look at a specific bed and breakfast in Alnwick called Chatton Park House. I really like it in there – good quality food, staff who attend to your needs and great value for money overall. The rooms are great, too – other places can feel quite cramped, but that is not the case.
One thing I like about Chatton Park, too, is how much room they have for parking. I was able to get parked here nicely and easily, while other places make it needlessly awkward.