The beauty of the vast variety of RV's, is that any one of them will allow you to take the family on fun adventures. The only question is, which one will best fit your needs and budget.
We are a family of four and have been enjoying our truck camper immensely. It may take a little more time to load (although it's never been a big deal to me), the benefits are HUGE from that point forward.
It's easy to get romanced by the space offered in tt, 5w and mh's, but the primary amenity they provide is dead air space. We haven't even hosted one ballroom dance in our rv yet. :) :) As others have said, I'm not trying to be offensive, but the fact is, a truck camper provides all the pertinent resources needed for a family of four, including sleeping accomodations (and this is coming from current, first-hand experience). I will say, a slide makes all the difference, because it provides elbow room when changing clothes and preparing meals. However, one factor that plays into the need for space, is the physical size of the family members. A family of body builders or NFL players, would likely be very challenged in a TC.
Our favorite feature of the truck camper is definitely maneuverability and ease of set-up. From zipping around gas stations, parking lots, FS roads, campgrounds, etc, it simply can't be beat. Then, once we pull into a campsite, usually we just put out slide and start playing. Very little tinkering around with everything under the sun.
One final thought - because of the maneuverability, we usually leave the camper on the truck during our camping trips and sightseeing excursions. This way, we have all our handi-dandi amenities with us - - especially, the restroom and food.
Bottom line: TC'ers can, and do, work with families of four, but other options also exist.
Good luck with your decision and have fun!