Thanks for all the replies! You can probably see from how I presented it that I too prefer #1. I have interview for #2 today, though they know I have to answer #1 by Wednesday. I plan to go to the interview with an open mind, but barring any dramatic experience, I think #1 makes more sense for my family, and for me.

That's easy---number 1

Definitely #1

I would also go for #1. I have found that class size is a much more significant issue than classroom space, assuming that you have a dedicated space and are not traveling between classrooms over the course of the day.

Personally I'm less concerned with the portables. My DS has been in them several years. The spaces are actually easier to set up - a square room makes set up of desks, school materials etc easier then some of the odd shape rooms in the building. Individual control over heating and cooling unlike the building where its only done at certain times each year. The kids do have to go into the building for bathroom use but my DS said that has rarely been a problem. I would say good quality teacher's and supportive parents are very important.

I agree with PP and would choose #1. I have taught in a portable classroom, and it really isn't bad as a teaching space.

I choose 1 for you. My DD is in what I call "a trailer park" but they call a portable classroom. This is her second year in one. I asked last year's teacher and this year's how they like not being in the building. Both (one is a teacher for decades and one is in her second year of teaching) really like it.

I am returning to full-time teaching after 8 years working part-time.

I have two positions that I am considering

Offer #1:
Pros:
10 minute commute (my gym is right nearby)
direct colleague that I would work closely with shares similar teaching philosophy
diverse school, as a result, smaller class sizes
Children seem to be eager to learn

Cons:
Portable classroom space for the forseeable future
high mobility rate, lose/gain many students throughout the year
Lower parent support

Possible offer #2: (will know tomorrow)
Pros:
Classroom in building
High level of parent support
Well established program in my field
Cons:
Teacher who is leaving has been there a long time (I worry about people being fixated on how she did things)-this is a pro and a con in a way
20 minute drive
Larger class size
Have heard that though parents are very involved, it can be taken to extremes

Decision will be made by this week, but I am struggling a bit on what is most important to me. If the Offer#1 had a permanent classroom space, I think that I would choose that school now. I have 3 children, at 2 schools. One school is more similar to #1, the other more similar to #2, thus far, I have much preferred #1.