When I decide to use miles for a free ticket, I will consider the price of the ticket first. If it's not too expensive, then I won't use miles. Also we should calculate miles that we'll get if we buy a ticket instead of using miles. For example, if I fly from SFO-BOS, I will have to use 25,000 miles or pay 350$ for a discounted ticket. If I pay, I will earn about 5000 base miles plus 5000 elite bonus. Then I have to compare between 10000+25000 = 35000 miles and 350$. Some miles should be reserved for some unexpected travel that might occur. Otherwise I'll have to buy an unbelieveably expensive ticket. I haven't found any good deal about redeeming miles for hotels, car rentals or vacation packages.