I have an F100 as well and I adore it...but it isn't a small camera. It usually doesn't bother me but when I want to travel lighter I use my Nikon FE. It is significantly smaller than the F100 (it fits nicely into a small camera bag where the F100 won't). Nice viewfinder, Aperture priority, meter etc and you can still shoot with it if your battery dies, but the batteries seem to last forever. I also own an Olympus Om-10. It's slightly more compact than the FE, a nice camera but I prefer the metering of the Nikon, which is dead on almost always...the OM-10 metering isn't as reliable, more overexposure I find.
I won't ever sell my F100, nor my FE for that matter. Keep it if you can and add a smaller camera to your collection. I got my FE for less than $100 and the Olympus for something like $40, with the 50mm 1.4, a terrific lens. Just my opinion anyway.