Desert Botanical Garden, for sure. Take the guided tour.
If you happen to be on the far east side of town, something similar to the Botanical Garden is Boyce Thompson Arboretum. I’m talking far east side; it’s about 25 miles east of Apache Junction on Hwy. 60.
2 hours north of Phoenix is Sedona, IMNSHO the most beautiful place on earth. If you feel like a day trip one day, I’d recommend that.
J.
If you do drive up to Sedona, you have to stop at Rock Springs Cafe in Black Canyon City either on your way there or back for some of the best pie you’ll ever eat!
If you feel like the drive - I would recommend Boyce over the Botanical Garden any day of the week.
If you’re into beer at all, I’d recommend Papago Brewing in Scottsdale. Brewpub/tap room/bottle shop. I only spent a weekend in the Phoenix area but I have to think it’s probably the best beer joint around.
Small nit-pick: It’s not actually at the entrance to the park. If you’re at the actual entrance to the park you’re too far south and west. Los Dos Molinos is at 8646 South Central Ave (corner of Euclid) and about 1-2 miles from the park entrance.
I only mention this to help find it. Someone unfamiliar with the park could be pretty confused ("Which gate house is the entrance? Is that building with the Ranger’s cars in front of it the restaurant?) Really neat restaurant.