From a very lapsed Mormon; if there is a new one going up in your area, you can visit new temples before they are dedicated or older ones that are being rededicated and get an idea of their structure during a kind of open house walk through. Some of the older ones are very beautiful, the more modern ones are what you might expect and rather spare and bland. I suspect that when the first Salt Lake temple is rededicated,(it has been under construction for earthquake resistant modifications for the last few years) the line to view it will be miles long or you will have to make reservations.