I've been using JuiceDefender for a couple of weeks now and I started another thread on it that's down the page a ways. My first try was to just install the free version and use the defaults. I've since bought the "Plus" version which allows you to customize your settings and affected apps.
Basically, JuiceDefender works good if you have sufficient downtime during the day that it can shut off the radios when the screen is off. If you're a heavy user and are constantly on the phone, your benifits won't be that great. I'm a moderate user at best, but do use a lot of data for e-mail and such. I get two to three hours more use from my battery than I did before under the same use.
Using the "Plus" version, I manually disabled the radios for apps that I don't use that show up as running and I can't kill off or uninistall. Some of these are City ID, Twitter for LG, BlockBuster, Weather Widget, etc.. Just doing this alone also gave me 30-40mb more available ram as well.
Just a couple of days ago, I found that the city I work in (Spokane, WA) went live with 4G LTE, so I went into the settings and turned on the 4G radio. I'm still figuring out the differences in power usage since then, but the jury hasn't come back yet.
I still thing the ultimate solution will be to root the phone and deal with the bloatware, but I'm not going to do that until Gingerbread comes along as I'm able to work within the system quite well now. - MarkC