Yeah, I use OnOne phototools 2 with CS5 also, although I typically only use it on portraits and sometimes for quick frame effects, but it definately comes in very handy.
Typically you would just be adjusting color,contrast,exposure, cropping and sharpening, but the sky is really the limit. Its harder to learn photoshop, but its also the best tool. So unless you do not do alot of Post Processing to your photos, you will eventually find yourself wanting photoshop over say lightroom, or Elements. Think of Elements and Lightroom as a chefs knife and photoshop CS5 as a scalpel. They both cut, but one is more of a precision instrument. One also isn't for the Novice. You can download a trial of all of them as recommended, but CS5 is going to take more than a few days to dig into, so don't write it off just because you didn't spend enough time on it during the trial. Lightroom and Elements is obviously aimed at beginners so the trials may seem much better to you because you will be able to do more faster. I started with Corel Paintshop Pro and dumped it in less than a week after reading up on some photoshop tutorials. I don't think I would still be doing photography if I still had paintshop Pro. Photoshop allowed me to get above average work from subpar photos ( while thats not how you want to work, as a beginner this can really help keep your confidence and motivation up ). Now I am just as interested in Post Processing whether its helping others, or doing my own photos, as I am with actually shooting.
Essentially it all boils down to money, if you can afford photoshop and have the time and patience to learn it ( the basics shouldn't take too long if you atleast are computer literate ) then why settle for something less.