Varies a lot with weather and whether it's a car camping trip or backpack-in trip.
My current car camping setup is a Marmot Limelite 2 tent set up at least half under a tarp which allows me in and out in the dry and gives room for cooking, etc under cover. I throw down a Cabela's cot pad and use an older Hollofill II semi-rectangular bag with a Thermarest down blanket to throw over the top if the bag is not warm enough. The whole thing breaths good so condensation is not an issue and it gives me plenty of bug-free space. I really like the bent-pole design on the tent because the sides go up vertically a foot or more before curving in which really increases the useful floor space.
Typically my backpacking is summer, not constant rain, maybe t-storms, hopefully not. I go pretty light.
The setup used most includes a Bearpaw Wilderness Designs bug bivy, a Thermarest NeoAir pad, and a Western Mountaineering MityLite bag. I generally pack a cuben fiber tarp as well .. just in case. The alternate setup uses the same pad and bag but exchanges the Bearpaw WD bivy for a ground sheet and an REI Bug Hut I. The BP WD bivy is lighter, the Bug Hut 1 is a little easier to get in and out of.
I have a bunch of other stuff to choose from if weather changes so I can really fine-tune my gear to conditions. I admit it, I'm a gear junkie / addict.
MIB