The flex-actin GFP and "GFP mouse" come to mind. The GFP mouse (Jax 003291) has GFP under the control of an actin promoter so it should be everywhere. The flex-actin mouse (029889) expresses TdTomato that is shut down after Cre recombination. The GFP mouse is fine and labels all neurons and other cells. A friend has worked with the flex-actin mouse and said the basal Tomato expression is very bright but bleaches fast.