Allison asked, "Another question, in general (although specifically I'm thinking winter packing, if the answer is different depending on the season) do the hammock set ups tend to be lighter weight or the same as tarps/bivvys/lightweight tents?"
Hammocks weigh a little more due to the hammock and the bottom insulation. Tarps are typically much larger than what an UL solo hiker would normally use. I guesstimate a 10oz-20oz weight increase for an ultralight hammock kit vs a typical UL solo ground camping rig. You still need a sleeping bag or quilt, so that is a wash.
You can use a CCF pad for insulation and save a lot of weight and money, but CCF pads aren't as comfy (or warm) as a well made under quilt. CCF pads work best with a double layer hammock. The Hennessy SuperShelter system is comfortable enough, but I rate it at about 40F and wouldn't try to push it any lower than 32F. It should be used with a space blanket as recommended. If you like the idea of an undercover-based system like the SuperShelter, I can expand on my experiences there.
See the Warbonnet web site for weights on components:
http://warbonnetoutdoors.com/blackbirds.php shows 20-27oz for the hammock body with suspension and integral insect net. Weights vary with single or double layer construction and fabric weight.
Check the same site for the range of tarp sizes and weights, and you can also get an overview of down under quilts. As with ground camping options, you can get silnylon, spinnaker, and Cuben fiber tarps and the same cost and weight issues. As I said before, with a little study, you can get a tarp that will work for ground camping too and extend your dollars.
Your body weight will make a difference in the options for the hammock body. The rest is simply what you prefer for weight of the components, temperature range and weather coverage. Hennessy makes some light backpacker-oriented packages for those under 200 pounds. You can go with the lighter Warbonnet models with single layer 1.1oz fabric too. If you are shorter as well, you can use the Scout model Hennessy which is really a bargain.
A shorter person can really capitalize on bottom insulation. I'm 5'10" and a 3/4 under quilt typically covers from shoulder to calf, so a smaller person can get more coverage for the same weight and cost.
Here is a breakdown of weight and cost of several hammock systems I put together for a forum member at hammockforums.net:
Here is a full hammock kit rated to 0F. I chose Warbonnet because it is accepted as quality gear and they make all the components for a complete system. Of course there are many other combinations...
Blackbird double layer 1.1 with strap suspension 27oz $175
(2) carabiners 2oz $15
Mamajamba Tarp 13oz $110
Winter Yeti under quilt 18.5oz $215
Mamba Winter top quilt 26.25oz $275.00
Total 86.75oz (5.4lbs/2.45kg) $790
For an inexpensive 3 season system you could do something like this:
Grand Trunk Ultralight $18 (about 16oz with a re-worked suspension)
Amsteel whoopie slings $18.50
Tree huggers $14.00
2x Camp Nano carabiners $15
Papa Smurf bug net 2.5oz $50
Gossamer Gear Thinlite wide CCF pad 12oz $30
Chinook Guide Tarp (12'x9.5') 28oz $45
North Face Cat's Meow mummy bag 44oz $125 (typical 3-season/20F synthetic bag)
Total 102.5oz (6.4lbs/2.9kg) $315.50 (note the bag is a huge portion of weight and cost)
Closer to what I have for 3 season:
Hennessy Expedition Zip 48.5oz $149 Includes suspension and tarp
Wilderness Logics synthetic 3/4 UQ 26oz $115
North Face Cat's Meow mummy bag 44oz $125
Total 118.5oz (7.4 lbs/ 3.4kg) $389