Don't worry about the insulation value of your sleeping pad, your mattress at home is much more insulating, and you can sleep on that.

The Therm-A-Rest air mattresses are great, but skip the self inflating kind, go for one with at least 2.5 inches of height. The Neo-Airs are great, but so are plenty of air mattresses from other manufacturers. My current favorite is the Exped Synmat, just as comfy as a Neo-Air, but doesn't make the slight crinkly noise (Not a big issue, but better to not have it).

If you're camping someplace where it gets even slightly chilly at night, a real sleeping bag might be in order. I have a LaFuma 45 degree bag that packs down to about two liters, weighs a pound and a half, and is great for when it's not cold. I bought it from the REI Outlet for something like $40, and it's been worth every penny.

If you just want something very light, it's hard to go wrong with a silk liner. Doesn't give much warmth, but if it doesn't get bellow 80 at night (Shakes fist at weather) that's fine.

If you want to buy a tent at REI, take a look at the new REI Dash, it looks like a great tent that's nearly weightless. The Sierra Designs Flashlight is also an intriguing idea, but one I want someone to test out before I commit to it myself. The Big Agnes Scout tent also has tons of fans. I've also been looking at REI tents, can you tell?