I like using styrene, especially the shaped strips such as angles, columns, channels, Z-bars, etc, for cars and passenger sheds. I like wood for structures and ships. I haven't used Gator Board, but do use foam mat board from hobby, craft and frame shops. For the shed you are planning to build, I would use scribed wood sheets, and strip wood for trim. The mat board would be too thick, and while the styrene would come out just as nice, I like the finishes you can duplicate with wood that are harder to do on styrene. Use the one you are most familiar with, and you will enjoy the project and the final product. When you start on larger buildings, you will need internal bracing. I use wood for this, and you can get various thickness in strips at most craft stores. I use wood glue for wood to wood and foam mat board to wood joints. I use styrene cement for styrene to styrene joins. For dissimiliar materials such as metal windows, styrene to wood and styrene to mat board, I now use the new UV cured 5-second glues. It has a pinpoint applicator, and once cured, holds well. I found that if there is going to be shear force on the joint, they separate eventhough the commercials say it won't. I find it at a major chain store, but I don't know if I can mention the name in this thread. I also use card stock, embossed styrene sheets, and embossed papers for sidings. I use the self-adhesive on the embossed paper sheets, or contact cement for the embossed styrene and card stock. Thin strips of wood between the structure and the sheet will let you line them up, and then pull out the strips from the center. Rub the two parts together to get rid of air bubbles as you remove the strips of wood. Wood for train cars that are metal or metal siding on buildings requires sanding sealer, and a lot of work to get the wood grain smooth as paper. I would recommend styrene for metal cars and metal siding on buildings. You may be able to find the metal sheets of corrugated metal to use on roofs and metal sided buildings. I haven't used it for years, but would use the contact cement to bond it to the structure. I know I have mentioned Gator Board, foam mat board and metal siding sheets that you weren't considering, but I like using the various products out there for different effects. Rod Stewart uses acryllic sheets for the core of his city buildings and adds windows and embossed sheets for the outer surfaces if you plan on building a skyscraper. Don't be confused by all the different materials. Take your time and you will like the results. Then you can make structures unique to your cities that you model, and found only on your layout. Good luck with your project.