The first thing I would do is trim the tree at least three feet back from the house. You could also fill in the landscaping a bit below the first floor windows. A picture directly facing the house would give an idea of the balance of the current landscaping. It sounds like you want to keep the current house color, but hate the brick. You could paint the brick or reface it in a stone that you prefer. If you are open to changing the house color, you could try charcoal grey or midnight/navy. Those colors would certainly modernize the house and the large windows on the first floor would prevent the house from looking too dark.

It looks like it wraps around to the front of the house, so you'll have to be careful. Have you tried using one of the painting sites to test out different colors? Have you thought about painting the wall brick the body color and leaving the chimney brick?