Assuming you have a not to exceed number in your looking budget, you have two options. Buy a smaller higher priced model with FG sides and a few more fancy items or a large lower priced mode with aluminum sides and a few less fancy items. With your family I would guess you would be happier with the additional space. You can always add upgrades to suit your needs when possible. Also if this is your first TT, and you are like most people, you will want something different is a few years. The resale value of an RV drops dramatically in the first few years then slows. The RV industry is booming and almost all manufacturers are not producing units of the same quality they did a few years ago. Do your research, find the one that fits your family and you can afford and don't worry where it fits on the comparison scale.
The salesperson's job is to get as much of your money as they can. Don't take your check book or CC when you go to look and even when you think you found the right one. Don't sign anything, go home talk it over ask questions and if you are still convinced it is the right one you can always go back the next day. Try to take the emotion out of the deal especially when around the dealer.
Make it FUN.
2015 Freedom Express 248RBS
TV 2015 Silverado HD2500 Duramax
TST Tire Monitors
Honda 2000I + Companion
2 65W solar panels