When my oldest son was that age, he loved to have movie parties and game parties. For a movie party, we'd get comfy in sleeping bags, pillows, bean bag chairs . . . whatever he wanted. We'd turn off the lights and pop popcorn and we'd all watch a movie he picked. For game parties, we'd make a fun snack of some kind and play games. If your son is almost 3, there are lots of games he can play now! At that age, my son loved Hungry Hungry Hippos, Candy Land, Don't Wake Daddy, Hullabaloo to name a few.
Another thing he liked doing was helping around the house with projects. Whether it was painting a room (I gave him a clean paint roller and he would "clean" the wall before I'd get to it), organizing a closet, cleaning the garage, he loved being involved and we got stuff done around the house!
Have you thought about joining somewhere that has an indoor pool? I don't know where you live, but there is a place in Keller and Denton that I know of, but I am sure there are more. Might be fun to go swimming on the weekends, even in the winter. My boys always liked browsing pet stores too. They loved looking at the birds and fish. My boys love to go to Cabela's too. If you haven't been there, kids like it. If he likes movies, now that he is almost 3, you could probably go to the movies with him.
That's all I can think of right now. I remember getting cabin fever on the weekends when my boys were little. Now that they are 5 and almost 8, our weekends usually consist of a sport of some kind. We had baseball for one and soccer for the other kid in the fall. Now, one boy is in basketball, and as soon as that's over, they'll both be in baseball all spring. Now that they are in school, there always seems to be a birthday party, school function, or something else going on. So, our weekends are never relaxing. Enjoy it while you can! We get excited if there is a weekend with nothing to do now!