Sentence structure help??? :'(

the 1st and the 3rd sentences are more appropriate than the 2nd

I think the third sentence is more appropriate. The second sentence uses the word yourself, which means the action returns to the action performer itself. However here the subject of the sub sentence is he. Besides, it's a habitual way of putting you before he/she.

Ooh! None of these sentences is very good. Let me suggest a slight modification.

His schedule for the early part of this week is tight, but he has indicated that on either Thursday or Friday (Oct. 9th & 10th) he could be available to meet with you and Dan to discuss the details.

You can say “meet with Dan and you,” or “meet with you and Dan.” Either will do. The decision can be based on who is more important, Dan or you. My recommendation would be to say “meet with you and Dan,” if there is any doubt.

It is not correct to say, “to meet with yourself and Dan.”

Incidentally, it is now considered somewhat old-fashioned to say “Oct. 9th & 10th.” Most modern writers would prefer “Oct. 9 & 10” However, many people still use the old method (Oct. 9th & 10th) so do not worry about changing this if you are more comfortable with it.