I have been a SAHM for 17 years. I have 3 children,
a daughter (17, and 2 sons (15 and 11). Like you, I looked for "activities" to do with my children. If I could do it over again, I would do things differently.
The habits they develop in the home now they will carry with them into their teen years and beyond.
I would start my day with them with a morning devotion. Then, make a picture check list for them to "get ready for their day" - BR, wash face, brush teeth, get dressed, make bed, etc. and get a sticker or an angel stamp when they're done.
Have them start a load of laundry with you. Having them sort by color teaches them, and, they love to help fold. They are so proud to show you what they can do.
Have them help you set the table for each meal. (You can draw on any piece of paper a table setting - plate/bowl in center, fork on left, butter knife and spoon on right), put it at a place and have them put each item on top until they can do it without the paper.
Have them help you get out the food and help prepare it. A great activity to do together is to bake bread/rolls. They are so proud when they can make it for Daddy!
Have them help clear and wash dishes. They feel very important wearing an apron.
Have them help you dust, vacuum, sweep, and clean BR.
I would buy a homeschooling curriculum for that age (Seton, Bob Jones and ABeka are ones that I am familiar with - they all have a website). That gives you lots to do, they learn a lot and they enjoy it; you will, too!
Get computer activities for preschoolers.
Get some large, wooden or plastic beads and string them, or penne noodles. Puzzles are great. Play games like Candyland or card games like fish. Count 100 cheerios or fruitloops.
Draw pictures or lines and circles, write the letters of the alphabet, spell his name and things in the house and label them.
Garden together, plant seeds (any kind - a cup with some grass seed grows quickly for them to see results soon, plant tomato plants - something that you can use or something that you like - flowers).
Sew together. My son sewed a pillow by himself for his new brother when he was born. It wasn't 'professional', but it was cute, and it was from his heart.
Plan a tea party together and dress up for it.
Get a bike seat and go riding together. Buy a pair of skates for both of you and go skating together out front.
Take walks, pack picnic lunches, feed the squirrels, birds, ducks. Use sidewalk chalk and bubbles.
Buy a plastic ball, bat and glove and play catch and hit (baseball). Buy a soccer ball and kick it around outside. Same with a little lacrosse stick and ball and a basketball and small hoop (or basket or bucket up on a chair).
Play jump rope and hopscotch (hopping and balancing and coordination).
Make mud pies, or flour pies, or play dough.
Sing together. Dance.
The library has lots of books with craft ideas.
Most importantly, look into his eyes and talk, just have a conversation. It will develop into a bond of love, trust and communication.
Don't forget to take some time for yourself.
Watch Super Nanny on ABC; she has great ideas.