Is it necessary to book now for an architectural cruise on October 31? I hate to pay the extra fees to Tickemaster if I don't have.

Putting a city in your heading will help lots.

ita.

I agree with putting Chicago in your header.

That said, fortunately we recently returned from Chicago and took the Architectural Cruise. HIGHLY recommended. You don't need to purchase your tickets that far in advance. You can buy them the date of the tour at the dock (go early), or anytime before in the lower patio of the John Hancock Building, they have a store there. No extra "service charge".

We went the day before to the John Hancock Building. No big deal since we were going to the 96th floor for a drink and view the city and surrounding area.
Also HIGHLY recommended.

Enjoy. It's really a beautiful city and cruise. Very informative.

An interesting aside on the cruise, they have a full bar on the boat. The cruise takes 90 minutes. I didn't see one person going to the bar even for a coke! I thought about getting a beer, but the narration and views were too compelling.
If I can pass up a beer or a drink, just about anybody can, believe me.

Curious

Ita, you should be alright if you can buy your tickets at least a day ahead of time. That's not peak tourist time for river cruises so it shouldn't be a problem. A word of warning---Chicago's Halloween weather is infamously awful. It can be 80 and sunny the day before and after and sleet and 40 Halloween day! Bring a coat!

I bought my tix the day before, thru my concierge. Bring a coat, gloves, hat, scarf.....it was windy so I felt like my ears were going to freeze and fall off my head!

Last time I was in Chicago the tours were already sold out for the following day. It was a weekend (I checked on Saturday for a Sunday cruise) and the season (late Spring) was busier than late October will be. I'd just reserve the day you get there for one onf the subsequent days of your visit.