Just stick 'em in the ground and step back! lol

Full sun and don't water them unless absolutely necessary (like, if they start to shrivel up). Mine go months without water. Opuntias are one of those plants that like to be left alone.

I've grown the Santa Rita, Black Spine, Beavertail, and a couple of hybrids and the only one I managed to kill was the Beavertail, which doesn't like our summer rain.

Huh, really? There's masses of them here (Beavertail, that is). I second everything Juttah said, with the addition of *very* well draining soil.

The Beavertail has been a favorite of mine - it has the blue/gray pads with bright pink blooms on them. The Santa Ritas are the round pad that is blue and gets a pink tone on it with cooler weather. The little "Bunny Ears" with either the yellow or white glochids can be cool when they get large (but be careful of the dang glochids - I'll take spines over them any day). Then there's the classic green with the red fruits - which I think is either the Opuntia engelmanii or ficus indica, or both.

Where there certain kinds that you liked?

You've got good taste. :) I love Opuntias and grow quite a few different types. Full hot sun, and only occasional water are all they want. When it's routinely above 100 F (38 C) I water mine every ten days or two weeks. Other than that, maybe water once a month. If the weather makes me feel cold, I don't water them at all. Just remember, if you buy some in pots, ask the seller which side has been facing south/west (the sunny side) so you don't put them in so that the shaded sides are suddenly on the sunny side. Most good growers put an X on the side that was in the sun.

Let us know what you select, and how it works out. They are fabulous, iconic plants. I handle mine with bbq tongs, by the way!

Have fun and post updates!
Take care,
Grant

Here is a link that might be useful: Pics, so far, from my garden, October 2012