salukigirl,
I think that it is great that you finally had a nice talk with your father ~ you both deserved that!
I do agree with Open Eyes. The decision is absolutely yours to make. My opinion is just that ~ my opinion. I would stick with the original plan. The step-mom's new plan doesn't sound real tempting to me. I would rather have those few special hours with my Dad, without adding the stress of more time in exchange for a weekend of stress.
That is my simple opinion. Best wishes to you on whatever decision you do make for yourself. My thoughts are with you!