Tina, My husband and I just bought a real fixer-upper house and we have the same problem. The cupboards are way too dark. I hate it because even though we have lots of windows (two in the kitchen and two rather large ones in the dining room, which is attached to the kitchen) we still have to have lights on in the kitchen in the daytime. Unfortunately we also had brown wood paneling. That came down almost immediately after we moved in, even though the walls looked awful underneath.
The first thing I did after removing the paneling was to go out and purchase a good belt sander. You would be amazed what this $128.00 investment can do. I tackled one cupboard door at a time. I did not even bother to clean them. I thought it would just be a waste of time. I took all the fixtures off the doors and took my sander right to it. Someone had redone these cupboards once before and had done an awful job. Once I got all the varnish, stain and filth off the door it looked brand new. I cleaned it up real good and varnished it without staining it at all. They are very light now and look just fantastic. One thing that I did notice is that the lighter the wood cupboards are the harder it is to see fingerprints and smudge marks and stuff. The way they were before they looked dirty all the time. No matter how hard I tried to get them clean they still looked dirty. Tess