An easy way to identify the 32-bit apps on your computer is to open "About This Mac" (under the Apple menu), click on "System Report" and in the sidebar scroll down to Software....
The issue isn't identifying which ones are 32 or 64 bit, it's wondering which ones will work on the next system upgrade. Many I can do without but I have a handful (e.g. Bento, Quicken, Graphic Converter, et cetera) that work just fine with High Sierra and which I would not like to replace.
I suppose the day will come when I'll be forced to adjust to less familiar software but I'd like to delay it as long as possible.
