We're a family of 4 in a 24' box. Each summer, we do 40+ day trips. We removed the dinet and installed a residential reclining loveseat. The kids sit in bean bags when we're couped up.
Honestly, the pros of being shorter have outweighed the cons for us. Many times we've been thankful we could squeeze into a site and only once or twice has someone commented on space.
It's going to be a different answer for everyone, but we made the right one for us.
I agree with all that's been said about payload. As your kids grow, you'll have less and less margin...if you have any at all now.