Question: Craig - I am looking for a gas insert for an existing masonry fireplace with a large firebox. I would like to take advantage of the large firebox and maximize the amount of flame visible from the room. I am also looking for a lot of heat and an excellent quality unit that will run all winter for years. Which units have the tallest viewing area? Total square inches? (Looking at both flush and bay models.) Best warranties? Also, I can't tell the difference in quality or biggest bang for the buck when shopping. FOr example, the Travis companies all have gas inserts, but I can't really tell a the Mercedes from the mule. (The same is true with the other companies as well. I haven't found anywhere that compares and rates gas inserts.) Answer: There is no rating service available on these products. I may decide to start one when I retire. The largest viewing area that I have seen in on the Mendota MIG-40 gas fireplace insert. This is a well-made product that will produce a good heat output. The Travis inserts work well, but are quite small...they designed them for the smaller fireplaces common in the Northwest. Some Bay models, such as the Osburn and Heat and Glo, may have as many sq inches as the Mendota (which is flat), but the Mendota still looks bigger due to the height of the glass and size of the log set. Update 2007 Travis gas insert windows are now quite a bit larger. Vermont Castings offers one of the larger viewing windows available as well.