CindySue, what cassette/freewheel are you running in back? It is the combo that you need to look at. Sheldon Brown has a nice gear calculatgor and articles on his web site that you let you easily see what you can accomplish with changes. One inner chainring is a minor investment and if you're careful not to crossgear you probably won't have to shorten you chain. Just swap back after the tour.

Depending on your cassette, you may just want to swap this for the tour.

Use the gear calculator and look at gear inches. I typically look for at least 2 inches difference to consider it a full gear lower.