I'm having a similar problem with my signal. After 9.5 hours at work with a consistent decent signal, I come home with 40% of my battery remaining which I figure should last me the rest of the night since I'll switch to wifi and not use it much.
But then apparently the signal jumps all over the place which is causing my battery to nosedive and need a charge a couple hours later. It doesn't make much sense since I work a block away from home, and when I look at the status screen at any given time in both places, it says similar numbers. between -88 and -92 and 54 asu. I've been in spots that are worse than -100 and according to gsam, it doesn't jump around as much as when I'm home.
If you look at this gsam shot, the parts where it plummets are the parts of my day where I'm home. In the morning, half hour lunch, and at the end of the day.
If you look at the history screen shots, you can see that when I'm home (the times where wifi is on), the signal bar goes from solid green to yellow, etc and back to green repeatedly.
The Verizon store guy thought it was completely normal, and said Samsung antennas suck.