I know, you wish that everyone could afford their own subscription to Ancestry.com but we know that's not possible. Even when visiting your local Family History Center you can access some data from Ancestry.com, but not all. Currently you have to use a subscription at your local library or one of the Family History Libraries for more complete access to the Ancestry.com databases.
However, there are over 260 FREE databases with information that might help you with your genealogical research and you can use them from the comfort of your home. You have FREE access to the indexes and in just a few cases you have the images. Then you ask, "What will indexes tell me when I can't see the images". Typically you get more clues and some direct evidence to help you piece together your jigsaw family history puzzle. But the trick here is to maximize your time and energy BEFORE you travel to your local library or Family History Center. Spending some time making your way through the free indexes and documenting what you find will help you do some final searching of the databases later, in less time.
The Ancestry Insider has put together a terrific spreadsheet of all the free databases on Ancestry.com, complete with links to each database. Check out the AI's list here. Utilize the data and then take your trip.