If your gear doesn't meet your needs as packaged: fix it! This is easier for some types of gear, and a sleeping pad is chief among them.
A sleeping pad is intended to provide your bones with some padding for the ground (more important for protecting the hips of scrawny side sleepers like me). Additionally, the sleeping pad insulates you from the ground to varying degrees by type and thickness of pad. If you sleep with your head on a pillow (or pack) and rest your feet on a pillow (or pack), you really only need a pad that reaches from your shoulders to your butt, no wider than your shoulders or hips.
Last year I took a Thermarest Ridgerest (the green one) and was pleased with it. I cut it down and was comfortable when I was carrying it and sleeping on it. This year, I'm trying a closed-cell foam pad (the blue ones they sell at REI). It's a little lighter and I think I'll be comfortable.
As a side note, the Ridgerest is lighter, cheaper and provides more insulation per unit area than the Z-rest which is advertised as packing into a smaller area. Most people pack sleeping pads outside of their pack so I'm not sure why this matters, and once you cut your pad down, it's negligible.
Here's why it's worth cutting your sleeping pad down:
Starting Size: 24.5" x 57"
Starting Weight: 213g (7.5 oz.)
Ending Size: 16.5" x 29"
Ending Weight: 70g (2.5oz.)
Weight Savings: 143g (5 oz.)