I'm making paella.
Most of the recipes I've looked at call for specialty rice varieties that are expensive and/or difficult to find. I have a large amount of Calrose rice (this stuff) in my cupboard already.
I know I want to avoid long-grain, very-non-sticky varieties like basmati, but aside from that I'm not sure what the important considerations are when choosing my rice. Is the Calrose I already have a good choice, or should I bite the bullet and buy something fancy?
Some will say no, some will say yes. I'm in the yes camp.
If you want to make paella, and that's the only rice you have on hand, don't let anyone stop you.
Use this as a learning experience.
Be warned that the rice might be stickier than other type or rice, especially paella rice, so be careful about the amount of liquid used.
Rinse the rice thoroughly to remove as much surface starch as possible.
Calrose rice is a medium grain rice, it will probably work okay but it won't really have the right texture. If you are in the US there shouldn't be any problem finding short grain Arborio rice, which is all that paella rice is. You can spend a bomb on paella rice in fancy bags imported from half way across the world, but it isn't really a different product from the risotto rice or the arborio rice you get for a fraction of the price at many supermarkets.
Any cheap short-grain rice will work as well for paella as for risotto. You can use The Authentic Varieties, which are usually blisteringly expensive, or just head to your local Asian market for a good array of short-grain rice. If you don't have an Asian market, the short-grain varieties are usually found at floor level in your supermarket, since long-grain seems to be the canonical fashionable type in the US at the moment.
Just be sure not to rinse off the starch as recommended by Max, since that will negate the properties you're getting the short grain for.