OP - to answer your question, I did Beyond this year with DS#1 for 2nd grade. Most weeks we only did it three days a week for the first 2/3 of the year, and then we went to four days a week. We have CBS on Wednesdays, which we will do again this year. We did some school in the afternoons, but I simply couldn't do a full day, so I felt, at the beginning of the year. We did co-op on Friday. I did NOT try to do 5 unit days each week. We just kept plugging along and did one day whenever we had full days. That being said, we only got thru unit 27 or 28 and I am okay with that. We did our LA and our math separately and even on Wednesdays so we weren't behind on those. I will likely never finish Beyond. [snicker]
Next year... we will still do Wednesdays at CBS and I think I will try to do a full day with one or the other child. I can't do two full days in a few hours, I do not believe. I am not sure yet about going to co-op. Leaning toward no. For what they give my family, they seem to take more away, in this season of our lives. Maybe another year or two I will feel the pendulum swing back the other way.

:D:D
IHT-
if you do the friday co-op, I don't think you can really expect to do much afterward, unless you left at lunch time.

It is exhausting and there are a lot of demands on the parents. BUT, if you don't teach in the co-op you may find your kids don't get a lot of the classes you want and you could just take stuff to do there with say, one child if s/he doesn't get into a class at that time.
Now if you did the Monday co-op... you could probably do school in the AM then do that after lunch.
I don't think we will do either this year. After 3 years of co-ops, I need a break.