We considered the 3100 when looking. We have had other units and found that when staying at locations where slides should not be used, or just stopping at a rest stop for lunch the ability to get to everything was important.
We also wanted a short unit since we double tow. We did not like the small bath area where everything is close. If someone is at the sink and someone needs to get to the toilet, Well you know.
We settled on a 2014 3150RL. You can get to the frig, stove, sink, the bath area with all the slides in. It is about 7" shorter than a 3100.
The closet by the entry door is perfect for a umbrella, jackets, the dog leash and the fold up 2 step thing you need to get to the high cabinets.
Your needs may be different but for us, the 3150RL was a better fit.
Jim