If you know you would not blow that print up very big, then it's better to save in a lower resolution but with a fine JPEG compression. Although it's hard to see, the artifacts might be noticeable if you change the levels or perform some sharpening process later.
I usually shoot in fine cos I like to crop a lot. However it can consume a lot of space for me and I rapidly run out of space when I do AEB(Auto Exposure Bracketing). Sometimes I will carry my Digimate if I anticipate running out of space.
If you are complaining about this, man... then you haven't even tried the RAW format yet... :sweat:
But do save in the highest quality you can get away with. It really allows for future correction much better than when you save it at a lower res and lose the ability to boost such details when needed later.