Floor vs. elevated? Ramp vs. tunnel?

[ms pixie riot]

We have plans sketched out for a 2x5 grid with an L-shaped upper loft for the girls. Most of what I've seen recommends that cages be elevated.

The cage will be in our living room, which is really the floor-room in my house. When I'm in there, I'm sitting on the floor, or lying on the floor, 90% of the time. Same with anyone else who visits! So in our situation, would it be okay to have the piggies at floor level, so that they're near us and easily pettable?

It's not a room we walk through, it has only one door, so we wouldn't tower over them. Lots of relaxing time is spent in there.

Also, in the cage, I was planning on using a ramp with a piece of carpet on it, but I see some cages using a piece of flexible plastic tubing. Is one preferable over the other? Or should I watch my piggies, and where they spend their time, to see if I can guess what they would like best?