where to drop trailer while visiting big cities

Nearest Campground should work. And give you a place to sleep at night over getting a $$$ motel room for 1-2 days.

I would looking for big box hardware stores like Home Depot, Lowes and Menards. Ask customer service there. Park away from entrances and portion of lot far away.
If during week, check for large church lots.

mrjspjr wrote:
as we travel to large urban areas we would like to drop our trailer and use our truck to tour the area.
does anyone have a list of secure places one can drop a trailer for a day or two?

I would guess any campground that has a opening will be happy to rent that spot to you. :S

A few hours, maybe. Is an RV park out of the question?