Victoria House is very nice, I use to work there. They have a wonderful ambiance and a great staff. In regard to the mainland, I would suggest several places: Hidden Valley, Chaa Creek, Blancaneaux, Banana Bank, Jaguar Paw...there are quite a few that are nice and each have their own uniqueness. It depends what you are looking for, do you prefer the pine ridge in the mountains or the experience of the jungle?
I use to have a tour operation out of Belize City so am quite familiar. I could give you lots more info if you want, feel free to email me email@example.com