Seeking Fun Activity/outing for My Almost 4 Year Old Son

Gosh... That's a tough one... keeping a 4 year old boy and grandma happy in Texas in July...
There's the new Lego store in Frisco. They often have special events (http://stores.lego.com/en-us/Frisco/events.aspx). Obviously, grandma's probably not into Legos, but you could combine it with a walk around Stonebriar and lunch.
Lunch at Rainforest Cafe in Grapevine.
Stroll around Gaylord Texan. They've got SummerFest going on through early September, every Thu-Sun. Includes mini train displays, cowboys on stilts, jugglers, etc. Parking is $10-$12. Then you could stop and have ice cream inside the atrium.
Maybe a trip to Bass Pro in Grapevine? They have lots of cool displays for kids (aquarium, stuffed animals, tents set up, etc. You could even do this in conjunction with the Rainforest lunch.
The last option is outside of your noted budget, but thought I'd throw it in there... Dallas World Aquarium is a fantastic place, both for 4 year old boys and for grandmas. However, it would run about $50 for the 3 of you, and they're not an organization that generally offers coupons.

Good Luck!
www.familyeguide.com Your guide to affordable family activities in Lewisville, Flower Mound, Highland Village, and the surrounding communities.

Keller Pointe has a nice pool. We took our son on the Forest Park miniature train and he loved it. Cheap too.

My camps on Lake Grapevine - www.AdventureDayCamps.com - are for ages 4-13 and I have a water slide, inflatable, and play area for my 4-6 year olds.

Give me a call and maybe we can work out where you bring them out and "play" with them at out camp for $10 each. I've been flexible and creative all summer for families in need and love enriching the lives of my campers!

I'd second the Forest Park miniature railroad in Ft. Worth - down by the zoo. http://www.fpmt.us/ Everyone ends up having a great time on it. You've got to watch the weather though because they don't operate when it gets really hot or when it's raining.

Not sure where you live, but the zoo is always great, I love the one in Gainsville because it only takes about 2 hours to get through the whole thing, and they can feed the giraffes at 10:30 for $1. There is an awesome park there too with a train to ride so you could bring a picnic lunch for after the zoo and play in the park and go on a train ride.
Going Bonkers could be fun in Lewisville by the mall but I doubt Grandma would want to participate; it's more of a spectator sport for grown-ups.
There is the science museum in Ft. Worth also or an imax film.