Look at floor plans and see what will work best for you/your family. Consider if you'll need a desk or bunks or more than one bathroom.
You'll have less concern about weight if you choose a tag (for the most part). But, you might also have less space underneath to carry stuff.
As Roadpilot noted, you can usually somewhere to stay in most areas even in a larger coach. (Just not every state and federal park though.)
Make sure you find the factory sticker for the GVWR and such information. Check the date codes on the tires so see how old they are. And don't let a salesperson talk you into a coach you know is not right for you, just because it's a "good deal".
Good luck and let us know what you decide on.
