Do a 15 year mortgage regardless and make sure you get the best rate you can now so you don't have to refinance later. I wish I would have went a little bigger in the living room and laundry room. I also wish I would have had the basement wired and rocked right away as it doesn't cost that much and is a pain later on. Very glad I went with a large garage and finished it right away. A sink in the garage is a must. Floor heat done right was one my smartest decisions. Lots of spigots outside are nice and electrical boxes also are nice. We went vinyl and it's not bad at all but for sound and strength I would probably spray foam the entire house if I were to do it over again.