Many genealogists have a goal to go to the Family History Library in Salt Lake City, Utah to do some on-site research. However, the question arises as to the difference between doing an on-site search at a library and doing the same searches online. The first thought that comes to mind is that there are still a huge number of records locked up on paper or microfilm that are not available at all on the Web. My question is this; do you want a trip to Salt Lake City, Utah or are you specifically interested in the genealogical resources of the Family History Library?
My criteria for making a special trip to Utah involves a cost/benefit analysis. Is the cost of traveling to Utah equal to or greater than the benefit I will accrue from the time at the Family History Library? This rules out the side benefits of ski trips, hikes in the mountains, visiting relatives and such that may provide an additional motive for travel to Utah and particularly Salt Lake City. In the past, this analysis has involved the rental cost of Family History Libraries Microfilm Collection. Presently, for example, the rental cost of one roll of microfilm is $7.50 for a short term microfilm rental. So it is easy to calculate the cost of the trip and compare it to the number of rolls of microfilm I want to view. After perhaps hundreds of trips to Utah, we know how long it takes and we can either camp out or stay with relatives so the cost of travel involves the time spent and the cost of gas.
But the further away you live from Salt Lake, the greater expense is involved in travel to the Library, hence, the number of rented rolls of microfilm many be very large before it offsets the cost of travel to the Library. As a side note, the rental cost of microfilm is a good unit of measurement for benefit. For example, you want to see if signing up for Ancestry.com is worth the cost. Think of it in terms of the number of corresponding microfilms you could rent for the same price, assuming, of course, that Ancestry.com had records not digitized yet by FamilySearch. So the present cost of Ancestry.com World Version is about 40 microfilm rentals. Another thought, this amount is about my cost for a trip to Utah when I drove a Chevy Truck. Now I drive my Prius and it is about 1/3 that amount or less for gas. You can use the same type of analysis for any of the other subscription websites.
Now, the basic rule here is any time you find a catalog entry in the Family History Library Catalog that you think might be useful, before you pop for the rental fee, make sure the same records are not online somewhere else. FamilySearch may not have been the only entity to have the record and someone else may have digitized it. So copy the name of the microfilm record and do a Google search to see if someone else has the record online for free.
One very fundamental thing you need to understand is that no records are entirely "free." Searching and finding records is a labor intensive activity. You can easily go to the Family History Library and spend and entire week searching and not find the exact records you are looking for. The idea here is to have a very specific agenda including a specific list of records available at the Library you want to search. In my case, the rental list takes the lead in establishing this priority. If you have other reasons for going to Salt Lake, then weighing those reasons against the unproductive time at the Family History Library is another way of evaluating the real cost.
I suppose you can guess that searching online is entirely different from searching in a library. Even searching a library catalog online is different from searching in a library. Using online search engines diminishes the possibility of discovering sources by merely in-depth browsing the shelves and also eliminates the possibility of discovering sources by simple recognition. Library catalogs allow the researcher to identify related subject matter by suggesting topics. This type of searching is referred to as precoordination. This is where the catalogers take the time to link subjects that are related to an initial search term. When you search online, the terms that appear in response to any particular search are not suggestive of any related terms, so the researcher has to come up with the related terms. This is called postcoordination searching. In other words, the relevant search terms are not suggested, they must be manufactured or created by the researcher.
This difference is significant. If you think about it, the chances of finding other relevant documents is greatly diminished online, unless you are either an extremely competent online researcher or working within the context of catalog entries. For an example what I am talking about, you may want to look at the Library of Congress Classification.
The simplest example I can think of, is the difference between "reading the shelves," that is looking at all the books in a section of a library and doing an online search for the same subject area. No matter how good you are in searching online, you cannot get the same results that you can from researching in a library.
My suggestion is that unless all this makes sense to you, you need to learn a little bit more about searching; both online and in a library such as the Family History Library before spending your time and money going to a library such as the Family History Library. I do not want to discourage anyone but on the other hand, I suggest you take the time to carefully study how to search online before you conclude that what you are looking for is not there and the same thing goes for searching in a library.