I just went shopping for the same antenna and I came to a couple conclusions.
First, there are three basic types of antennas; scanner antennas (Austin Condor, RS deluxe, etc), HAM antennas (Diamond, Comet, Pryme, and a few others), and band specific antennas (Antennex, Comtelco, Larsen, Smiley). For your purpose, the HAM antennas would suit you well.
Second, for HAM antennas, there are many makes and models, but very few designs. Everybody offers the same basic antennas, so don't kill yourself finding the "magic"antenna. Some common ones are a 15-17" dual band - Diamond RH77, Pryme RD78, Comet CH75, MFJ 1717, Anli RD88, and Watson W881, and the 7-8" dual band "rat tail"- Diamond RH519, Pryme RD 9, MFJ 1716, Watson W801, and Comet SMA503 (SMA only). Comet and Pryme also make a 17" version. The longer antennas will perform a little better. Both the long and shorter ones are a vast improvement over a stock antenna.
From what I gathered from my research, Diamond, Comet, and Pryme seem to have a good reputation. MFJ's quality control seems to be so-so, and Watson's seem to be a little on the pricey side.
Here are a few good places to look.
http://www.universal-radio.com/catalog/hamantht.html
http://www.hamcity.com/
http://www.randl.com/shop/index.shtml
I went with the Diamond RH77 and Pryme RD 9 and am pretty happy with both.