Right now through Halloween offers a great time for spontaneous travel with frequent flier miles you may have trouble otherwise redeeming.

This past Friday afternoon, I learned that everybody in my house was busy for the weekend except for myself and my 7-year-old son Grant.  So I went online and saw frequent flier seats at the lowest possible redemption rate to city after city, for going Friday and coming back Sunday.

I cross-checked weather and general hotel availability for different cities. In 15 minutes, I decided on Boston. My son and I were on the plane 100 minutes later.

We started our flight with no hotel arrangements whatsoever. While in the air, I used the free wifi to do Priceline bids. I ended up with a 4 star in central Boston $99, which is more than I wanted to pay.

My son had the best time ever. At the monument at Bunker Hill, he ran all 300 steps up to the top while all of us adults were huffing and puffing. The cost of Bunker Hill? Free.

We also went to the USS Constitution for free. We walked the Freedom Trail and went to Boston Commons for free. The cost of the carousel at Boston Commons and souvenirs? $3 and $15, respectively.

The big expense was the Duck-mobile, a vehicle that I took Grant on that drives on land and then goes in the Charles River. The cost? $22 for him and $27 for me with my military discount.

The thing is, this month and through Halloween, there is not a lot of tourist activity in walking cities like Boston, New York, Chicago, and San Francisco. And the weather in the northern climes especially is great. The daytime was 70 in Boston, though it did go down to 40 at night.

If you can flex where you go and book something at the last minute, that is the sweet spot for travel right now.