Help With Bike - Triple Crank or Compact?

Here's my opinion....

I had a double 1990's trek with a 53/42 crank and 7 speeds on the back.  It sucked when riding in hilly areas.  I switched my wifes trek over from a triple to a compact double with 8 speeds in the back.  I now ride a triple with 8 speeds in the back.  The compact is by far much lighter than a triple and gives you almost as much gearing as a triple.  A triple is nicer if you have fewer gears in the back like 8.  If you have a double front derailure and doubleshifters I would switch to a compact due to cost.  If you have 8 speeds in the back, you may need to space out the outer ring with a thin shim because your 8 speed chain MAY rub a little on the 50 gear when in the 34 gear due to the chain being a little wider than a 9 or 10 speed chain.      

The first question that needs to be asked is what cassette are you running on the rear.  They come in a ton of different combinations and since you are planning on getting rid of the ride soon I would start there.  That will be the cheapest solution.  If you aren't already riding a cassette with a 28 tooth large gear already, that is where I would start.  

Cassettes are described by the small and large teeth numbers.  For example, most bikes come from the manufacturer with an 12-25 or an 11-25.  Picking up three teeth on the rear cassette will make a huge difference.  Here is a good link to start some research......  http://www.cyclingsite.com/lists_articles/gearing_101.htm

I agree with what's above.  Best bang for the buck is a 12-27 cassette if you don't already have one.  Next, a compact double crank.  Last resort if that combo doesn't work for you, a triple.  With that said, if you aren't a strong cyclist, there is nothing wrong with going for the triple.  You will have to replace your shifter as well as the crank if you go that route, and probably also the rear derailleur.

For most people a compact crank is the right answer, IMHO.  I've been riding compacts since I got into tris and cycling, and with an 11-25 rear cassette I've got plenty of gears for climbing and don't spin out until almost 40 mph.  With a 12-27 you may find that you have plenty of gears as well.

This was so good it needed to be posted again! 

I would only add that you should check your current cranks to see what the gearing is.  Many bikes are coming from the factory with compact cranksets.  A compact will have 50/34 gearing and <most> standard cranksets will have a 53/39.  Another option you should look at is the length of your crank arms.  Adding a longer crank arm could provide better leverage while climbing.