An inclusive classroom set up should be uncrowded. I mean this in a few ways:
1) Students, regardless of whether they are typically mobile or use wheelchairs or other assistive devices, should be able to get around the whole classroom easily. The reality is that it's not always possible to do this because most schools were not built with inclusion in mind. We can do our best with what we've got by removing any furniture that isn't directly useful to our students. This means that if space is tight we toss our bulky teacher's desk and cabinets of materials that only we use. We make the aisles wide and try to create some open spaces when possible. Again, the reality is that most of us teach in classes that are too small for the number of students we have and as teachers we hate to get rid of anything. However, it's imperative that we do what we can in order to make it possible for all students to attend and be included in our classes.
Another word about why this is important: We've all felt like so much cattle in a pen when we've been squeezed into a tiny space with a large number of people. This is insulting just about whenever it occurs but extremely so when it's in an educational setting. Overcrowding in schools sends a terrible message to our students about the value of their education. Furthermore, when students with emotional and/or behavioral issues are added in, we have to assume difficult behavior will be the result. And it would be unfair to entirely blame a student for acting out in this situation.
2) Though hanging up posters and charts is very important, it's also important that it is clear to all students where they should be focusing their attention. I like hanging up charts to remind students of what we've been working on and as references for them. However, too many make it so that some students just block them out entirely as they home in on the salient information while other students who find it difficult to determine saliency (students with learning disabilites, ADHD, etc) lose their focus. Aside from being careful with packing our classrooms with furniture, we must be careful of packing our classrooms with visual stimuli.
3) Much has been written about the arrangement of desks in a classroom- whether all desks should be in rows or cooperative groups and whether the classroom should be arranged so as to clearly channel attention toward the front where, presumably, the teacher is standing or so that students are facing each other. In my experience it's important to pick a method and stick with it so that students are not wondering/worrying about where they will be sitting as they're walking to your classroom. Being able to balance students' needs for accessing other students at times while being able to work privately at other times is important and being able to make the transition between the two predictable and smooth will help many students shed their anxiety over seating.
As with all planning, we must considering that any student, not just the typical ones, may come to our classrooms and it will be our responsibility to include them to the full extent possible.