When ever someone revives a thread long dormant, I go back to the beginning and see if it already had good or bad or dated information.
Sarah, you posted on this thread 4 years ago!
As usual, there are a lot of people posting their experiences, but little "information" about why you want a certain wattage, and really the tricks of heat and thermal mass for tricky stuff like soldering a small bit to a large one (wire to track, detail bit to a large brass loco).
Reading back you can pull this out it pieces, but it is over 4 pages.
So my 2 cents:
Spend the money and buy a quality unit for your soldering of wires.
- temperature controlled
- temperature readout
- many options for replacement tips
- come with stand and tip wiper (wet sponge or the silvery ribbon ball)
For track, you want a physically large tip and attached copper part. You don't need super high wattage, but you need a lot of thermal mass, so as the rail tries to suck all the heat out, the iron has a "store house" of heat to keep the joint at soldering temperature. A big, old ugly thing usually works great.
Another thing that works great for track is a "gun" which is basically a transformer and the tip is the transformer output, they can make a lot of heat. The downside is they are pretty uncontrollable, so you have to get used to it, but some have dual temperatures and you might find one where you don't have to modulate the switch on and off.
Early someone in the thread suggested a gas powered iron. They indeed heat fast, and you can modulate the temperature easily. But you have no idea what the temperature is. The biggest drawback is the heat from the flame and sometimes the flame itself is usually exhausted sideways, and you can burn stuff up off to the side easily, please ask me how I know.. I do have one, but I use it for very specialized cases, like pinpoint heating the axle screws on Aristo loco that are slathered with red loctite.
Greg