"We" is a personal pronoun like: I you he she it we you they but "our" is a possesive pronoun and means that something belongs to someone, for example: Mine Yours His Her Its Our Yours Their "Us" is a an object pronoun like: Me You Him Her It us you them this ones follow a personal pronoun once a personal pronoun is been already used. We can not say: I talked to He the correct for is "I talked to him" Hope I helped you, my name is Uri Quintal, I am a profesional online English and Spanish teacher currently working for a Mexican University. I offer some different courses focused on helping students not only to speak a second language but to think and dream in another language for a very low cost. If you are interested please contact me. Have a nice day! :)

"Our" is possessive. Because the weekend plan was made by us, it is ours. Our is not the subject of the sentence, but plan is, and "our" talks about "plan." If you want to use "we," you must use it as a subject. The thing that does something in the sentence. You could say, "We plan to..."

"Our" is possessive. "We" just indicates a group of people. By saying "our weekend plan", you say that it is yours, not someone else's. "