So I've got 3 days to do something. The website says I can use my miles to buy a ticket on Southwest or JetBlue or for an itinerary on Orbitz.

Problem: I have no trips planned just now.

General question: Is there a way to bank my miles for later use?

Specific question: I am wondering if I can/should buy a completely changeable ticket for a distant date? But 'completely changeable' usually means higher cost.

Advice will indeed be appreciated by this new user who read about the forum in Parade this morning, perhaps just in time. Thanks.