Things to do in the Valley

Hello everyone, I am planning a surprise trip to Yosemite at the end of December for my one year anniversary with my girlfriend. Neither of us have ever been there and I have no idea what to do while there. We’re going to go in Yosemite Valley for a whole day and want to do as much as possible for that day. If you could give me any tips or recommendations that would be great, we’re pretty adventurous and open to anything. Views are the goal and any must sees would also be helpful, thank you ahead of time!