Finding a parking place

First, I'd recommend you tow a car if you like to do a lot of city look-sees. However, as we traveled secondary roads all the time even with our 40' motorhome we had no problem finding a place to park if we wanted to stop at a local diner for lunch. In small towns we find our space either just before entering Main St. or just after. There are usually better places on a side street or in a grocery parking lot, etc.

Depends on the town. Many towns along the Oregon coast have height limit signs, "no vehicle parking over 7ft". These towns usually offer bus/large vehicle parking at some end of town lot. Even with our 38ft motorhome towing a car we have always found parking in towns across America (west of the Mississippi, as we haven't been east with the MH). There is usually a city park, a central church, or just an empty lot available. Now cities are a whole different story.

If the towns are small and tight enough to have limited parking, you probably don't want to be there in a big RV anyway. Been there, done that, had to disconnect and back out. Several times.

My question is "when traveling through towns around the country, how difficult is it to find parking if you want to stop and walk around the town"?

In many of the tourist/coastal towns in this area it's very difficult. Bar Harbor, ME, Gloucester, MA, Rockport, MA, Gettysburg, PA, Concord/Lexington, MA and many of the other key areas have limited parking in general.

Do you mean park or do you mean camp?

https://freecampsites.net/

If you are looking for parking in a big city downtown areas like Chicago, Detroit, Philadelphia - good luck. You will probably parking at a mall, shopping center, or big box store further out and taking the bus downtown.

We have a 38ft 5th wheel plus a 21ft long truck to tow it with. We have always been able to find a place to park in towns throughout the U.S.

Some of the spots we've used with permission:
Church Parking Lots
Grocery Stores
City Hall
City or County parks
Library
Manufacturing Plant or Warehouse
RV Parks

I can find parking in small towns most of the time with my truck and '32 5th wheel so you should have no problem. Now a city is a whole different story.

In my somewhat limited experience with my 32' long motorhome, it hasn't been too much of a difficulty, though of course it is harder than with a car. I basically need two normal parking spaces end-to-end lengthwise, or a strip of perhaps a half dozen side-by-side. In smallish towns and suburbia, this isn't too difficult to manage. In big cities...well, I plan ahead to avoid the problem by camping close enough to public transportation to be able to use that (and otherwise generally avoid driving through the heart of the city).

Naturally the details vary a great deal with what specific town you're talking about and on whether or not you'll be towing something. On the other hand, I don't think the precise length of the motorhome makes as much difference for parking once you generally can't fit in a single parking space.