1. When touring in the US there is often the possibility to pitch a tent on a covered concrete slab. For instance, many city parks offer that option and it is typically very much welcomed by most cyclists even though the ground is bone hard.
Also there is the option of sleeping inside a barn, shed etc. But to keep out the bugs, people prefer to use their tent - at least the inner tent without the fly.
2. I myself usually choose a concrete slab to avoid the condensation inside the tent in the morning. If I have condensation I will always need to dry my tent at midday - an action which requires 10-30 min of my time while eating lunch. It is still annoying however and thus I will always seek for a covered area for my tent.
3. When setting up a tent on a hard floor a freestanding tent is mandatory. A tunnel tent will never work. For that reason many people have chosen a freestanding tent for their cross country trip.
4. A freestanding tent is usually always heavier than a non freestanding tent. So that is the major disadvantage of freestanding tents - they need more and longer poles that add weight. I think is not too wrong to say that a 2 person freestanding tent usually weighs 4-5 pounds and a 2 person non freestanding tent weighs 2-3 pounds.
5. When riding the Transam I think I had the option of pitching my tent on concrete 10-20% of the time. So this is now when you have to decide if it is worth it to carry the extra weight in order to have added comfort 10-20% of the time.
Entering my new idea:
Use a 2-3 pound non freestanding tent and for example 4 cords each being 15 feet long:
Sea to summit reflective accesssory cord in the 1,8mm versionhttp://www.seatosummit.com/product/?item=Reflective+Accessory+Cord&o1=0&o2=0&o3=820
33 feet of cord weights only 0.5 ounce totalling 1 ounce for the 4 cords. Of course you can split the 4 cords into even smaller ones if you like.
With these cords, I can attach them to the main cords of the non freestanding tent and extend them to trees, benches, chairs, barbecue stoves etc - stuff which is usually common in city parks. You can also use your bicycle or trailer as a dead weight for some of the cords. That way I can use a non freestanding tent on a concrete slab - but only because on all my trips I noticed there are ALWAYS attachment points somewhere close by.
When setting up the tent there is the annoyance of attaching the extra cords, but I think if I only have to do it 10-20% of the time it is OK. If I was sleeping on concrete 100% of the time I would never do it.
I have not tried the above idea yet, but soon I will. You are welcome to comment.